void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    double *vec, *retVec, TT1,TT2;
    double rb[3][3], rp[3][3], rbp[3][3];
    mxArray *retMATLAB;
    size_t i, numItems;

    if(nrhs!=3) {
        mexErrMsgTxt("Wrong number of inputs");
        return;
    }

    if(nlhs>1) {
        mexErrMsgTxt("Wrong number of outputs");
        return;
    }

    numItems=mxGetN(prhs[0]);
    if(mxGetM(prhs[0])!=3) {
        mexErrMsgTxt("vec has the wrong dimensionality. It must be an 3XN matrix.");
        return;
    }
    checkRealDoubleArray(prhs[0]);
    vec=(double*)mxGetData(prhs[0]);

    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);

    //Allocate the return vector
    retMATLAB=mxCreateDoubleMatrix(3,numItems,mxREAL);
    retVec=mxGetData(retMATLAB);

    //Call the IAU function to get the rotation matrix.
    iauBp06(TT1, TT2, rb, rp, rbp);

    //Invert the rotation matrix by transposing it.
    iauTr(rb, rb);
    for(i=0; i<numItems; i++) {
        //Multiply the original vectors by the matrix to put it into the ICRS.
        iauRxp(rb, vec+3*i, retVec+3*i);
    }

    //Set the return value.
    plhs[0]=retMATLAB;
}
Example #2
0
void iauBp06(double date1, double date2,
             double rb[3][3], double rp[3][3], double rbp[3][3])
/*
**  - - - - - - - -
**   i a u B p 0 6
**  - - - - - - - -
**
**  Frame bias and precession, IAU 2006.
**
**  This function is part of the International Astronomical Union's
**  SOFA (Standards Of Fundamental Astronomy) software collection.
**
**  Status:  support function.
**
**  Given:
**     date1,date2  double         TT as a 2-part Julian Date (Note 1)
**
**  Returned:
**     rb           double[3][3]   frame bias matrix (Note 2)
**     rp           double[3][3]   precession matrix (Note 3)
**     rbp          double[3][3]   bias-precession matrix (Note 4)
**
**  Notes:
**
**  1) The TT date date1+date2 is a Julian Date, apportioned in any
**     convenient way between the two arguments.  For example,
**     JD(TT)=2450123.7 could be expressed in any of these ways,
**     among others:
**
**             date1         date2
**
**         2450123.7           0.0       (JD method)
**         2451545.0       -1421.3       (J2000 method)
**         2400000.5       50123.2       (MJD method)
**         2450123.5           0.2       (date & time method)
**
**     The JD method is the most natural and convenient to use in
**     cases where the loss of several decimal digits of resolution
**     is acceptable.  The J2000 method is best matched to the way
**     the argument is handled internally and will deliver the
**     optimum resolution.  The MJD method and the date & time methods
**     are both good compromises between resolution and convenience.
**
**  2) The matrix rb transforms vectors from GCRS to mean J2000.0 by
**     applying frame bias.
**
**  3) The matrix rp transforms vectors from mean J2000.0 to mean of
**     date by applying precession.
**
**  4) The matrix rbp transforms vectors from GCRS to mean of date by
**     applying frame bias then precession.  It is the product rp x rb.
**
**  Called:
**     iauPfw06     bias-precession F-W angles, IAU 2006
**     iauFw2m      F-W angles to r-matrix
**     iauPmat06    PB matrix, IAU 2006
**     iauTr        transpose r-matrix
**     iauRxr       product of two r-matrices
**
**  References:
**
**     Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855
**
**     Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981
**
**  This revision:  2009 December 17
**
**  SOFA release 2012-03-01
**
**  Copyright (C) 2012 IAU SOFA Board.  See notes at end.
*/
{
   double gamb, phib, psib, epsa, rbt[3][3];


/* B matrix. */
   iauPfw06(DJM0, DJM00, &gamb, &phib, &psib, &epsa);
   iauFw2m(gamb, phib, psib, epsa, rb);

/* PxB matrix. */
   iauPmat06(date1, date2, rbp);

/* P matrix. */
   iauTr(rb, rbt);
   iauRxr(rbp, rbt, rp);

   return;

/*----------------------------------------------------------------------
**
**  Copyright (C) 2012
**  Standards Of Fundamental Astronomy Board
**  of the International Astronomical Union.
**
**  =====================
**  SOFA Software License
**  =====================
**
**  NOTICE TO USER:
**
**  BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
**  CONDITIONS WHICH APPLY TO ITS USE.
**
**  1. The Software is owned by the IAU SOFA Board ("SOFA").
**
**  2. Permission is granted to anyone to use the SOFA software for any
**     purpose, including commercial applications, free of charge and
**     without payment of royalties, subject to the conditions and
**     restrictions listed below.
**
**  3. You (the user) may copy and distribute SOFA source code to others,
**     and use and adapt its code and algorithms in your own software,
**     on a world-wide, royalty-free basis.  That portion of your
**     distribution that does not consist of intact and unchanged copies
**     of SOFA source code files is a "derived work" that must comply
**     with the following requirements:
**
**     a) Your work shall be marked or carry a statement that it
**        (i) uses routines and computations derived by you from
**        software provided by SOFA under license to you; and
**        (ii) does not itself constitute software provided by and/or
**        endorsed by SOFA.
**
**     b) The source code of your derived work must contain descriptions
**        of how the derived work is based upon, contains and/or differs
**        from the original SOFA software.
**
**     c) The names of all routines in your derived work shall not
**        include the prefix "iau" or "sofa" or trivial modifications
**        thereof such as changes of case.
**
**     d) The origin of the SOFA components of your derived work must
**        not be misrepresented;  you must not claim that you wrote the
**        original software, nor file a patent application for SOFA
**        software or algorithms embedded in the SOFA software.
**
**     e) These requirements must be reproduced intact in any source
**        distribution and shall apply to anyone to whom you have
**        granted a further right to modify the source code of your
**        derived work.
**
**     Note that, as originally distributed, the SOFA software is
**     intended to be a definitive implementation of the IAU standards,
**     and consequently third-party modifications are discouraged.  All
**     variations, no matter how minor, must be explicitly marked as
**     such, as explained above.
**
**  4. You shall not cause the SOFA software to be brought into
**     disrepute, either by misuse, or use for inappropriate tasks, or
**     by inappropriate modification.
**
**  5. The SOFA software is provided "as is" and SOFA makes no warranty
**     as to its use or performance.   SOFA does not and cannot warrant
**     the performance or results which the user may obtain by using the
**     SOFA software.  SOFA makes no warranties, express or implied, as
**     to non-infringement of third party rights, merchantability, or
**     fitness for any particular purpose.  In no event will SOFA be
**     liable to the user for any consequential, incidental, or special
**     damages, including any lost profits or lost savings, even if a
**     SOFA representative has been advised of such damages, or for any
**     claim by any third party.
**
**  6. The provision of any version of the SOFA software under the terms
**     and conditions specified herein does not imply that future
**     versions will also be made available under the same terms and
**     conditions.
*
**  In any published work or commercial product which uses the SOFA
**  software directly, acknowledgement (see www.iausofa.org) is
**  appreciated.
**
**  Correspondence concerning SOFA software should be addressed as
**  follows:
**
**      By email:  [email protected]
**      By post:   IAU SOFA Center
**                 HM Nautical Almanac Office
**                 UK Hydrographic Office
**                 Admiralty Way, Taunton
**                 Somerset, TA1 2DN
**                 United Kingdom
**
**--------------------------------------------------------------------*/
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    size_t numRow,numVec;
    mxArray *retMat;
    double *xVec, *retData;
    double TT1, TT2, UT11, UT12;
    //The if-statements below should properly initialize all of the EOP.
    //The following initializations to zero are to suppress warnings when
    //compiling with -Wconditional-uninitialized.
    double dX=0;
    double dY=0;
    double xp=0;
    double yp=0;
    double deltaT=0;
    double LOD=0;
    double ITRS2GCRS[3][3];
    double TIRS2GCRS[3][3];
    double invrPom[3][3];//Inverse polar motion matrix. TIRS=IPOM*ITRS.
    double Omega[3];

    if(nrhs<3||nrhs>7){
        mexErrMsgTxt("Wrong number of inputs");
    }
    
    if(nlhs>2) {
        mexErrMsgTxt("Wrong number of outputs.");
        return;
    }
    
    checkRealDoubleArray(prhs[0]);
    
    numRow = mxGetM(prhs[0]);
    numVec = mxGetN(prhs[0]);
    
    if(!(numRow==3||numRow==6)) {
        mexErrMsgTxt("The input vector has a bad dimensionality.");
    }
    
    xVec=(double*)mxGetData(prhs[0]);
    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);
    
    //If some values from the function getEOP will be needed.
    if(nrhs<=6||mxIsEmpty(prhs[3])||mxIsEmpty(prhs[4])||mxIsEmpty(prhs[5])||mxIsEmpty(prhs[6])) {
        mxArray *retVals[5];
        double *xpyp, *dXdY;
        mxArray *JulUTCMATLAB[2];
        double JulUTC[2];
        int retVal;
        
        //Get the time in UTC to look up the parameters by going to TAI and
        //then UTC.
        retVal=iauTttai(TT1, TT2, &JulUTC[0], &JulUTC[1]);
        if(retVal!=0) {
            mexErrMsgTxt("An error occurred computing TAI.");
        }
        retVal=iauTaiutc(JulUTC[0], JulUTC[1], &JulUTC[0], &JulUTC[1]);
        switch(retVal){
            case 1:
                mexWarnMsgTxt("Dubious Date entered.");
                break;
            case -1:
                mexErrMsgTxt("Unacceptable date entered");
                break;
            default:
                break;
        }
        
        JulUTCMATLAB[0]=doubleMat2Matlab(&JulUTC[0],1,1);
        JulUTCMATLAB[1]=doubleMat2Matlab(&JulUTC[1],1,1);

        //Get the Earth orientation parameters for the given date.
        mexCallMATLAB(5,retVals,2,JulUTCMATLAB,"getEOP");
        mxDestroyArray(JulUTCMATLAB[0]);
        mxDestroyArray(JulUTCMATLAB[1]);
        
        checkRealDoubleArray(retVals[0]);
        checkRealDoubleArray(retVals[1]);
        if(mxGetM(retVals[0])!=2||mxGetN(retVals[0])!=1||mxGetM(retVals[1])!=2||mxGetN(retVals[1])!=1) {
            mxDestroyArray(retVals[0]);
            mxDestroyArray(retVals[1]);
            mxDestroyArray(retVals[2]);
            mxDestroyArray(retVals[3]);
            mxDestroyArray(retVals[4]);
            mexErrMsgTxt("Error using the getEOP function.");
            return;
        }
        
        xpyp=(double*)mxGetData(retVals[0]);
        dXdY=(double*)mxGetData(retVals[1]);
        xp=xpyp[0];
        yp=xpyp[1];
        dX=dXdY[0];
        dY=dXdY[1];
        
        //This is TT-UT1
        deltaT=getDoubleFromMatlab(retVals[3]);
        LOD=getDoubleFromMatlab(retVals[4]);
        //Free the returned arrays.
        mxDestroyArray(retVals[0]);
        mxDestroyArray(retVals[1]);
        mxDestroyArray(retVals[2]);
        mxDestroyArray(retVals[3]);
        mxDestroyArray(retVals[4]);
    }
    
    //If deltaT=TT-UT1 is given
    if(nrhs>3&&!mxIsEmpty(prhs[3])) {
        deltaT=getDoubleFromMatlab(prhs[3]);
    }
    
    //Obtain UT1 from terestrial time and deltaT.
    iauTtut1(TT1, TT2, deltaT, &UT11, &UT12);
    
    //If no values for the polar motion coordinates are given, then use
    //zeros.
    if(nrhs>4&&!mxIsEmpty(prhs[4])) {
        size_t dim1, dim2;
        
        checkRealDoubleArray(prhs[4]);
        dim1 = mxGetM(prhs[4]);
        dim2 = mxGetN(prhs[4]);
        
        if((dim1==2&&dim2==1)||(dim1==1&&dim2==2)) {
            double *xpyp=(double*)mxGetData(prhs[4]);
        
            xp=xpyp[0];
            yp=xpyp[1];
        } else {
            mexErrMsgTxt("The celestial pole offsets have the wrong dimensionality.");
            return;
        }
    }
    
    if(nrhs>5&&!mxIsEmpty(prhs[5])) {
        size_t dim1, dim2;
        
        checkRealDoubleArray(prhs[5]);
        dim1 = mxGetM(prhs[5]);
        dim2 = mxGetN(prhs[5]);
        
        if((dim1==2&&dim2==1)||(dim1==1&&dim2==2)) {
            double *dXdY=(double*)mxGetData(prhs[5]);
        
            dX=dXdY[0];
            dY=dXdY[1];
        } else {
            mexErrMsgTxt("The polar motion coordinates have the wrong dimensionality.");
            return;
        }
    }
    
    //If LOD is given
    if(nrhs>6&&!mxIsEmpty(prhs[6])) {
        LOD=getDoubleFromMatlab(prhs[6]);
    }
    
    //Compute the rotation matrix for going from ITRS to GCRS as well as
    //the instantaneous vector angular momentum due to the Earth's rotation
    //in TIRS coordinates.
    {
    double x, y, s, era, sp;
    double rpom[3][3], rc2i[3][3];
    double GCRS2ITRS[3][3];
    double omega;
        
    //Get the X,Y coordinates of the Celestial Intermediate Pole (CIP) and
    //the Celestial Intermediate Origin (CIO) locator s, using the IAU 2006
    //precession and IAU 2000A nutation models.
    iauXys06a(TT1, TT2, &x, &y, &s);
    
    //Add the CIP offsets.
    x += dX;
    y += dY;
    
    //Get the GCRS-to-CIRS matrix
    iauC2ixys(x, y, s, rc2i);
    
    //Find the Earth rotation angle for the given UT1 time.
    era = iauEra00(UT11, UT12);
    
    //Get the Terrestrial Intermediate Origin (TIO) locator s' in radians
    sp=iauSp00(TT1,TT2);
    
    //Get the polar motion matrix
    iauPom00(xp,yp,sp,rpom);
    
    //Combine the GCRS-to-CIRS matrix, the Earth rotation angle, and the
    //polar motion matrix to get a transformation matrix to get the
    //rotation matrix to go from GCRS to ITRS.
    iauC2tcio(rc2i, era, rpom,GCRS2ITRS);
    
    //To go from the ITRS to the GCRS, we need to use the inverse rotation
    //matrix, which is just the transpose of the rotation matrix.
    iauTr(GCRS2ITRS, ITRS2GCRS);
    
    //Next, to be able to transform the velocity, the rotation of the Earth
    //has to be taken into account. This requires first transforming from
    //ITRS to TIRS coordinates, where the rotational axis is the z-axis.
    //That transformation requires the inverse polar motion matrix, which,
    //being a rotation matrix, is given by its transpose.
    iauTr(rpom, invrPom);
    //Then, one must transform from TIRS to GCRS, which can be done by
    //taking the inverse of the rotation matrix from GCRS to ITRS computed
    //using the identity matrix for polar motion (i.e. no polar motion
    //means leaving it in the TIRS.
    {
        double rident[3][3]={{1,0,0},{0,1,0},{0,0,1}};
        double GCRS2TIRS[3][3];
        iauC2tcio(rc2i, era, rident,GCRS2TIRS);
        iauTr(GCRS2TIRS, TIRS2GCRS);
    }
    
    //The angular velocity vector of the Earth in the TIRS in radians.
    omega=getScalarMatlabClassConst("Constants","IERSMeanEarthRotationRate");
    //Adjust for LOD
    omega=omega*(1-LOD/86400.0);//86400.0 is the number of seconds in a TT day.
    Omega[0]=0;
    Omega[1]=0;
    Omega[2]=omega;
    }

    //Allocate space for the return vectors.
    retMat=mxCreateDoubleMatrix(numRow,numVec,mxREAL);
    retData=(double*)mxGetData(retMat);
    {
        size_t curVec;
        for(curVec=0;curVec<numVec;curVec++) {
            //Multiply the position vector with the rotation matrix.
            iauRxp(ITRS2GCRS, xVec+numRow*curVec, retData+numRow*curVec);
            
            //If a velocity vector was given.
            if(numRow>3) {
                double posTIRS[3];
                double velTIRS[3];
                double *posITRS=xVec+numRow*curVec;
                double *velITRS=xVec+numRow*curVec+3;//Velocity in GCRS
                double *retDataVel=retData+numRow*curVec+3;
                double rotVel[3];
                //If a velocity was provided with the position, then first
                //convert into the TIRS, then account for the rotation of
                //the Earth, then rotate into the GCRS.
                
                //Convert velocity from ITRS to TIRS.
                iauRxp(invrPom, velITRS, velTIRS);
                //Convert position from ITRS to TIRS
                iauRxp(invrPom, posITRS, posTIRS);
                
                //Evaluate the cross product for the angular velocity due
                //to the Earth's rotation.
                iauPxp(Omega, posTIRS, rotVel);
                
                //Add the instantaneous velocity due to rotation.
                iauPpp(velTIRS, rotVel, retDataVel);
                
                //Rotate from TIRS to GCRS
                iauRxp(TIRS2GCRS, retDataVel, retDataVel);
            }
        }
    }
    plhs[0]=retMat;
    
    if(nlhs>1) {
        double *elPtr;
        size_t i,j;
        
        plhs[1]=mxCreateDoubleMatrix(3,3,mxREAL);
        elPtr=(double*)mxGetData(plhs[1]);
        
        for (i=0;i<3;i++) {
            for(j=0;j<3;j++) {
                elPtr[i+3*j]=ITRS2GCRS[i][j];
            }
        }
    }
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    size_t numRow,numVec;
    mxArray *retMat;
    double *retData;
    double ITRS2TIRS[3][3];//Inverse polar motion matrix
    double *xVec, TT1, TT2;
    double xp=0;
    double yp=0;//The polar motion coordinates
    
    if(nrhs<3||nrhs>4){
        mexErrMsgTxt("Wrong number of inputs");
    }
    
    if(nlhs>2) {
        mexErrMsgTxt("Wrong number of outputs.");
    }
    
    numRow = mxGetM(prhs[0]);
    numVec = mxGetN(prhs[0]);
    
    if(!(numRow==3||numRow==6)) {
        mexErrMsgTxt("The input vector has a bad dimensionality.");
    }
    
    checkRealDoubleArray(prhs[0]);
    xVec=(double*)mxGetData(prhs[0]);
    
    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);
    //If xpyp should be found using the function getEOP.
   if(nrhs<4||mxIsEmpty(prhs[3])) {
        mxArray *retVals[1];
        double *xpyp;
        mxArray *JulUTCMATLAB[2];
        double JulUTC[2];
        int retVal;
        
        //Get the time in UTC to look up the parameters by going to TAI and
        //then UTC.
        retVal=iauTttai(TT1, TT2, &JulUTC[0], &JulUTC[1]);
        if(retVal!=0) {
            mexErrMsgTxt("An error occurred computing TAI.");
        }
        retVal=iauTaiutc(JulUTC[0], JulUTC[1], &JulUTC[0], &JulUTC[1]);
        switch(retVal){
            case 1:
                mexWarnMsgTxt("Dubious Date entered.");
                break;
            case -1:
                mexErrMsgTxt("Unacceptable date entered");
                break;
            default:
                break;
        }
        
        JulUTCMATLAB[0]=doubleMat2Matlab(&JulUTC[0],1,1);
        JulUTCMATLAB[1]=doubleMat2Matlab(&JulUTC[1],1,1);

        //Get the Earth orientation parameters for the given date.
        mexCallMATLAB(1,retVals,2,JulUTCMATLAB,"getEOP");
        mxDestroyArray(JulUTCMATLAB[0]);
        mxDestroyArray(JulUTCMATLAB[1]);
        
        checkRealDoubleArray(retVals[0]);
        if(mxGetM(retVals[0])!=2||mxGetN(retVals[0])!=1) {
            mxDestroyArray(retVals[0]);
            mexErrMsgTxt("Error using the getEOP function.");
            return;
        }
        
        xpyp=(double*)mxGetData(retVals[0]);
        xp=xpyp[0];
        yp=xpyp[1];

        //Free the returned array.
        mxDestroyArray(retVals[0]);
    }
    
     //Get polar motion coordinates, if given.
    if(nrhs>3&&!mxIsEmpty(prhs[3])) {
        size_t dim1, dim2;
        
        checkRealDoubleArray(prhs[3]);
        dim1 = mxGetM(prhs[3]);
        dim2 = mxGetN(prhs[3]);
        
        if((dim1==2&&dim2==1)||(dim1==1&&dim2==2)) {
            double *xpyp=(double*)mxGetData(prhs[3]);
        
            xp=xpyp[0];
            yp=xpyp[1];
        } else {
            mexErrMsgTxt("The polar motion coordinates have the wrong dimensionality.");
            return;
        }
    }

    //Get the rotation matrix from TIRS to ITRS.
    {
        double sp;
        double TIRS2ITRS[3][3];//Polar motion matrix
        //Get the Terrestrial Intermediate Origin (TIO) locator s' in
        //radians
        sp=iauSp00(TT1,TT2);
        
        //Get the polar motion matrix
        iauPom00(xp,yp,sp,TIRS2ITRS);
        
        //The inverse polar motion matrix is given by the transpose of the
        //polar motion matrix.
        iauTr(TIRS2ITRS, ITRS2TIRS); 
    }
    
    //Allocate space for the return vectors.
    retMat=mxCreateDoubleMatrix(numRow,numVec,mxREAL);
    retData=(double*)mxGetData(retMat);

    {
    size_t curVec;
    for(curVec=0;curVec<numVec;curVec++) {
        //Multiply the position vector with the rotation matrix.
        iauRxp(ITRS2TIRS, xVec+numRow*curVec, retData+numRow*curVec);
        
        //Multiply the velocity vector with the rotation matrix.
        if(numRow>3) {
            double *velITRS=xVec+numRow*curVec+3;//Velocity in ITRS
            double *retDataVel=retData+numRow*curVec+3;//Velocity in ITRS

            //Convert velocity from ITRS to TIRS.
            iauRxp(ITRS2TIRS, velITRS, retDataVel);
        }
    }
    }

    plhs[0]=retMat;
    if(nlhs>1) {
        double *elPtr;
        size_t i,j;
        
        plhs[1]=mxCreateDoubleMatrix(3,3,mxREAL);
        elPtr=(double*)mxGetData(plhs[1]);
        
        for (i=0;i<3;i++) {
            for(j=0;j<3;j++) {
                elPtr[i+3*j]=ITRS2TIRS[i][j];
            }
        }
    }
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    double TT1,TT2,*xVec;
    double deltaT=0;
    double LOD=0;
    size_t numRow,numVec;
    double CIRS2TIRS[3][3];
    double TIRS2CIRS[3][3];
    double Omega[3];//The rotation vector in the TIRS
    mxArray *retMat;
    double *retData;

    if(nrhs<3||nrhs>5){
        mexErrMsgTxt("Wrong number of inputs");
    }
    
    if(nlhs>2) {
        mexErrMsgTxt("Wrong number of outputs.");
    }
    
    checkRealDoubleArray(prhs[0]);
    
    numRow = mxGetM(prhs[0]);
    numVec = mxGetN(prhs[0]);
    
    if(!(numRow==3||numRow==6)) {
        mexErrMsgTxt("The input vector has a bad dimensionality.");
    }
    
    xVec=(double*)mxGetData(prhs[0]);
    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);
        
    //If some values from the function getEOP will be needed
    if(nrhs<=4||mxIsEmpty(prhs[3])||mxIsEmpty(prhs[4])) {
        mxArray *retVals[5];
        mxArray *JulUTCMATLAB[2];
        double JulUTC[2];
        int retVal;
        
        //Get the time in UTC to look up the parameters by going to TAI and
        //then UTC.
        retVal=iauTttai(TT1, TT2, &JulUTC[0], &JulUTC[1]);
        if(retVal!=0) {
            mexErrMsgTxt("An error occurred computing TAI.");
        }
        retVal=iauTaiutc(JulUTC[0], JulUTC[1], &JulUTC[0], &JulUTC[1]);
        switch(retVal){
            case 1:
                mexWarnMsgTxt("Dubious Date entered.");
                break;
            case -1:
                mexErrMsgTxt("Unacceptable date entered");
                break;
            default:
                break;
        }
        
        JulUTCMATLAB[0]=doubleMat2Matlab(&JulUTC[0],1,1);
        JulUTCMATLAB[1]=doubleMat2Matlab(&JulUTC[1],1,1);

        //Get the Earth orientation parameters for the given date.
        mexCallMATLAB(5,retVals,2,JulUTCMATLAB,"getEOP");
        mxDestroyArray(JulUTCMATLAB[0]);
        mxDestroyArray(JulUTCMATLAB[1]);
        
        //We do not need the polar motion coordinates.
        mxDestroyArray(retVals[0]);
        //We do not need the celestial pole offsets.
        mxDestroyArray(retVals[1]);

        //This is TT-UT1
        deltaT=getDoubleFromMatlab(retVals[3]);
        LOD=getDoubleFromMatlab(retVals[4]);
        //Free the returned arrays.
        mxDestroyArray(retVals[2]);
        mxDestroyArray(retVals[3]);
        mxDestroyArray(retVals[4]);
    }

    //If deltaT=TT-UT1 is given
    if(nrhs>3&&!mxIsEmpty(prhs[3])) {
        deltaT=getDoubleFromMatlab(prhs[3]);
    }
    //If LOD is given
    if(nrhs>4&&!mxIsEmpty(prhs[4])) {
        LOD=getDoubleFromMatlab(prhs[4]);
    }
    
    //Compute the rotation matrix for going from CIRS to TIRS as well as
    //the instantaneous vector angular momentum due to the Earth's rotation
    //in GCRS coordinates.
    {
        double UT11, UT12;
        double era, omega;
        //Obtain UT1 from terestrial time and deltaT.
        iauTtut1(TT1, TT2, deltaT, &UT11, &UT12);
 
        //Find the Earth rotation angle for the given UT1 time. 
        era = iauEra00(UT11, UT12);
        
        //Construct the rotation matrix.
        CIRS2TIRS[0][0]=1;
        CIRS2TIRS[0][1]=0;
        CIRS2TIRS[0][2]=0;
        CIRS2TIRS[1][0]=0;
        CIRS2TIRS[1][1]=1;
        CIRS2TIRS[1][2]=0;
        CIRS2TIRS[2][0]=0;
        CIRS2TIRS[2][1]=0;
        CIRS2TIRS[2][2]=1;     
        iauRz(era, CIRS2TIRS);
        
        //To go from the TIRS to the GCRS, we need to use the inverse rotation
        //matrix, which is just the transpose of the rotation matrix.
        iauTr(CIRS2TIRS, TIRS2CIRS);
        
        //Next, to be able to transform the velocity, the rotation of the Earth
        //has to be taken into account. 

        //The angular velocity vector of the Earth in the TIRS in radians.
        omega=getScalarMatlabClassConst("Constants","IERSMeanEarthRotationRate");
        //Adjust for LOD
        omega=omega*(1-LOD/86400.0);//86400.0 is the number of seconds in a TT
                                    //day.
        Omega[0]=0;
        Omega[1]=0;
        Omega[2]=omega;
    }
    
    //Allocate space for the return vectors.
    retMat=mxCreateDoubleMatrix(numRow,numVec,mxREAL);
    retData=(double*)mxGetData(retMat);
    {
        size_t curVec;
        for(curVec=0;curVec<numVec;curVec++) {
            //Multiply the position vector with the rotation matrix.
            iauRxp(TIRS2CIRS, xVec+numRow*curVec, retData+numRow*curVec);
            
            //If a velocity vector was given.
            if(numRow>3) {
                double *posTIRS=xVec+numRow*curVec;
                double *velTIRS=xVec+numRow*curVec+3;//Velocity in GCRS
                double *retDataVel=retData+numRow*curVec+3;
                double rotVel[3];

                //Evaluate the cross product for the angular velocity due
                //to the Earth's rotation.
                iauPxp(Omega, posTIRS, rotVel);
                
                //Add the instantaneous velocity due to rotation.
                iauPpp(velTIRS, rotVel, retDataVel);
                
                //Rotate from TIRS to GCRS
                iauRxp(TIRS2CIRS, retDataVel, retDataVel);
            }
        }
    }
    plhs[0]=retMat;
    
    if(nlhs>1) {
        double *elPtr;
        size_t i,j;
        
        plhs[1]=mxCreateDoubleMatrix(3,3,mxREAL);
        elPtr=(double*)mxGetData(plhs[1]);
        
        for (i=0;i<3;i++) {
            for(j=0;j<3;j++) {
                elPtr[i+3*j]=TIRS2CIRS[i][j];
            }
        }
    }
}
Example #6
0
File: bp06.c Project: tohka/celes
void iauBp06(double date1, double date2,
             double rb[3][3], double rp[3][3], double rbp[3][3])
/*
**  - - - - - - - -
**   i a u B p 0 6
**  - - - - - - - -
**
**  Frame bias and precession, IAU 2006.
**
**  Status:  support function.
**
**  Given:
**     date1,date2  double         TT as a 2-part Julian Date (Note 1)
**
**  Returned:
**     rb           double[3][3]   frame bias matrix (Note 2)
**     rp           double[3][3]   precession matrix (Note 3)
**     rbp          double[3][3]   bias-precession matrix (Note 4)
**
**  Notes:
**
**  1) The TT date date1+date2 is a Julian Date, apportioned in any
**     convenient way between the two arguments.  For example,
**     JD(TT)=2450123.7 could be expressed in any of these ways,
**     among others:
**
**             date1         date2
**
**         2450123.7           0.0       (JD method)
**         2451545.0       -1421.3       (J2000 method)
**         2400000.5       50123.2       (MJD method)
**         2450123.5           0.2       (date & time method)
**
**     The JD method is the most natural and convenient to use in
**     cases where the loss of several decimal digits of resolution
**     is acceptable.  The J2000 method is best matched to the way
**     the argument is handled internally and will deliver the
**     optimum resolution.  The MJD method and the date & time methods
**     are both good compromises between resolution and convenience.
**
**  2) The matrix rb transforms vectors from GCRS to mean J2000.0 by
**     applying frame bias.
**
**  3) The matrix rp transforms vectors from mean J2000.0 to mean of
**     date by applying precession.
**
**  4) The matrix rbp transforms vectors from GCRS to mean of date by
**     applying frame bias then precession.  It is the product rp x rb.
**
**  Called:
**     iauPfw06     bias-precession F-W angles, IAU 2006
**     iauFw2m      F-W angles to r-matrix
**     iauPmat06    PB matrix, IAU 2006
**     iauTr        transpose r-matrix
**     iauRxr       product of two r-matrices
**
**  References:
**
**     Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855
**
**     Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981
**
**  This revision:  2009 December 17
**
**  Original version 2012-03-01
**
**  Copyright (C) 2013 Naoki Arita.  See notes at end.
*/
{
   double gamb, phib, psib, epsa, rbt[3][3];


/* B matrix. */
   iauPfw06(DJM0, DJM00, &gamb, &phib, &psib, &epsa);
   iauFw2m(gamb, phib, psib, epsa, rb);

/* PxB matrix. */
   iauPmat06(date1, date2, rbp);

/* P matrix. */
   iauTr(rb, rbt);
   iauRxr(rbp, rbt, rp);

   return;

/*----------------------------------------------------------------------
**
**  Celes is a wrapper of the SOFA Library for Ruby.
**
**  This file is redistributed and relicensed in accordance with 
**  the SOFA Software License (http://www.iausofa.org/tandc.html).
**
**  The original library is available from IAU Standards of
**  Fundamental Astronomy (http://www.iausofa.org/).
**
**
**
**
**
**  Copyright (C) 2013, Naoki Arita
**  All rights reserved.
**
**  Redistribution and use in source and binary forms, with or without
**  modification, are permitted provided that the following conditions
**  are met:
**
**  1 Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
**
**  2 Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in
**    the documentation and/or other materials provided with the
**    distribution.
**
**  3 Neither the name of the Standards Of Fundamental Astronomy Board,
**    the International Astronomical Union nor the names of its
**    contributors may be used to endorse or promote products derived
**    from this software without specific prior written permission.
**
**  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
**  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
**  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
**  FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
**  COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
**  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
**  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
**  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
**  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
**  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
**  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
**  POSSIBILITY OF SUCH DAMAGE.
**
**--------------------------------------------------------------------*/
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    size_t numRow,numVec;
    mxArray *retMat;
    double *xVec, *retData;
    double TT1, TT2, UT11, UT12;
    //The if-statements below should properly initialize all of the EOP.
    //The following initializations to zero are to suppress warnings when
    //compiling with -Wconditional-uninitialized.
    double xp=0;
    double yp=0;
    double deltaT=0;
    double LOD=0;
    double ITRS2TEME[3][3];
    double PEF2TEME[3][3];
    double WInv[3][3];//The inverse polar motion matrix to go from ITRS to PEF.
    double Omega[3];//The angular velocity vector for the Earth's rotation.
    
        
    if(nrhs<3||nrhs>6){
        mexErrMsgTxt("Wrong number of inputs");
    }
    
    if(nlhs>2) {
        mexErrMsgTxt("Wrong number of outputs.");
        return;
    }
 
    checkRealDoubleArray(prhs[0]);
    
    numRow = mxGetM(prhs[0]);
    numVec = mxGetN(prhs[0]);
    
    if(!(numRow==3||numRow==6)) {
        mexErrMsgTxt("The input vector has a bad dimensionality.");
    }
    
    xVec=(double*)mxGetData(prhs[0]);
    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);
    
    //If some values from the function getEOP will be needed
    if(nrhs<6||mxIsEmpty(prhs[3])||mxIsEmpty(prhs[4])||mxIsEmpty(prhs[5])) {
        mxArray *retVals[5];
        double *xpyp;
        mxArray *JulUTCMATLAB[2];
        double JulUTC[2];
        int retVal;
        
        //Get the time in UTC to look up the parameters by going to TAI and
        //then UTC.
        retVal=iauTttai(TT1, TT2, &JulUTC[0], &JulUTC[1]);
        if(retVal!=0) {
            mexErrMsgTxt("An error occurred computing TAI.");
        }
        retVal=iauTaiutc(JulUTC[0], JulUTC[1], &JulUTC[0], &JulUTC[1]);
        switch(retVal){
            case 1:
                mexWarnMsgTxt("Dubious Date entered.");
                break;
            case -1:
                mexErrMsgTxt("Unacceptable date entered");
                break;
            default:
                break;
        }
        
        JulUTCMATLAB[0]=doubleMat2Matlab(&JulUTC[0],1,1);
        JulUTCMATLAB[1]=doubleMat2Matlab(&JulUTC[1],1,1);

        //Get the Earth orientation parameters for the given date.
        mexCallMATLAB(5,retVals,2,JulUTCMATLAB,"getEOP");
        mxDestroyArray(JulUTCMATLAB[0]);
        mxDestroyArray(JulUTCMATLAB[1]);
        
        checkRealDoubleArray(retVals[0]);
        checkRealDoubleArray(retVals[1]);
        if(mxGetM(retVals[0])!=2||mxGetN(retVals[0])!=1||mxGetM(retVals[1])!=2||mxGetN(retVals[1])!=1) {
            mxDestroyArray(retVals[0]);
            mxDestroyArray(retVals[1]);
            mxDestroyArray(retVals[2]);
            mxDestroyArray(retVals[3]);
            mxDestroyArray(retVals[4]);
            mexErrMsgTxt("Error using the getEOP function.");
            return;
        }
        
        xpyp=(double*)mxGetData(retVals[0]);
        xp=xpyp[0];
        yp=xpyp[1];
        //The celestial pole offsets are not used.
        
        //This is TT-UT1
        deltaT=getDoubleFromMatlab(retVals[3]);
        LOD=getDoubleFromMatlab(retVals[4]);
        //Free the returned arrays.
        mxDestroyArray(retVals[0]);
        mxDestroyArray(retVals[1]);
        mxDestroyArray(retVals[2]);
        mxDestroyArray(retVals[3]);
        mxDestroyArray(retVals[4]);
    }
    
    //If deltaT=TT-UT1 is given
    if(nrhs>3&&!mxIsEmpty(prhs[3])) {
        deltaT=getDoubleFromMatlab(prhs[3]);
    }
    
    //Obtain UT1 from terestrial time and deltaT.
    iauTtut1(TT1, TT2, deltaT, &UT11, &UT12);
    
    //Get polar motion values, if given.
    if(nrhs>4&&!mxIsEmpty(prhs[4])) {
        size_t dim1, dim2;
        
        checkRealDoubleArray(prhs[4]);
        dim1 = mxGetM(prhs[4]);
        dim2 = mxGetN(prhs[4]);
        
        if((dim1==2&&dim2==1)||(dim1==1&&dim2==2)) {
            double *xpyp=(double*)mxGetData(prhs[4]);
        
            xp=xpyp[0];
            yp=xpyp[1];
        } else {
            mexErrMsgTxt("The celestial pole offsets have the wrong dimensionality.");
            return;
        }
    }
    
    //If LOD is given
    if(nrhs>5&&!mxIsEmpty(prhs[5])) {
        LOD=getDoubleFromMatlab(prhs[5]);
    }

    {
     double GMST1982=iauGmst82(UT11, UT12);
     double TEME2PEF[3][3];
     double TEME2ITRS[3][3];
     double W[3][3];
     double omega;
    
     //Get Greenwhich mean sidereal time under the IAU's 1982 model. This
     //is given in radians and will be used to build a rotation matrix to
     //rotate into the PEF system.
     GMST1982=iauGmst82(UT11, UT12);
     {
         double cosGMST,sinGMST;
         cosGMST=cos(GMST1982);
         sinGMST=sin(GMST1982);
         //Build the rotation matrix to rotate by GMST about the z-axis. This
         //will put the position vector in the PEF system.
         TEME2PEF[0][0]=cosGMST;
         TEME2PEF[0][1]=sinGMST;
         TEME2PEF[0][2]=0;
         TEME2PEF[1][0]=-sinGMST;
         TEME2PEF[1][1]=cosGMST;
         TEME2PEF[1][2]=0;
         TEME2PEF[2][0]=0;
         TEME2PEF[2][1]=0;
         TEME2PEF[2][2]=1.0;
     }
     //The inverse rotation is just the transpose
     iauTr(TEME2PEF, PEF2TEME);
     //To go from PEF to ITRS, we need to build the polar motion matrix
     //using the IAU's 1980 conventions.
     {
         double cosXp,sinXp,cosYp,sinYp;
         cosXp=cos(xp);
         sinXp=sin(xp);
         cosYp=cos(yp);
         sinYp=sin(yp);
         W[0][0]=cosXp;
         W[0][1]=sinXp*sinYp;
         W[0][2]=sinXp*cosYp;
         W[1][0]=0;
         W[1][1]=cosYp;
         W[1][2]=-sinYp;
         W[2][0]=-sinXp;
         W[2][1]=cosXp*sinXp;
         W[2][2]=cosXp*cosYp;
     }
     //The inverse rotation is just the transpose
     iauTr(W, WInv);
     
     //The total rotation matrix is thus the product of the two rotations.
     //TEME2ITRS=W*TEME2PEF;
     iauRxr(W, TEME2PEF, TEME2ITRS);
     //We want the inverse rotation
     iauTr(TEME2ITRS, ITRS2TEME);
     //The angular velocity vector of the Earth in the TIRS in radians.
     omega=getScalarMatlabClassConst("Constants","IERSMeanEarthRotationRate");
     //Adjust for LOD
     omega=omega*(1-LOD/86400.0);//86400.0 is the number of seconds in a TT day.
     Omega[0]=0;
     Omega[1]=0;
     Omega[2]=omega;     
    }
    
    //Allocate space for the return vectors.
    retMat=mxCreateDoubleMatrix(numRow,numVec,mxREAL);
    retData=(double*)mxGetData(retMat);
    
    {
        size_t curVec;
        
        for(curVec=0;curVec<numVec;curVec++) {
            //Multiply the position vector with the rotation matrix.
            iauRxp(ITRS2TEME, xVec+numRow*curVec, retData+numRow*curVec);
            //If a velocity vector was given.
            if(numRow>3) {
                double *posITRS=xVec+numRow*curVec;
                double *velITRS=xVec+numRow*curVec+3;//Velocity in TEME
                double posPEF[3];
                double velPEF[3];
                double *retDataVel=retData+numRow*curVec+3;
                double rotVel[3];
                //If a velocity was provided with the position, first
                //convert to PEF coordinates, then account for the rotation
                //of the Earth, then rotate into TEME coordinates.
                
                //Convert velocity from ITRS to PEF.
                iauRxp(WInv, velITRS, velPEF);
                //Convert position from ITRS to PEF
                iauRxp(WInv, posITRS, posPEF);

                //Evaluate the cross product for the angular velocity due
                //to the Earth's rotation.
                iauPxp(Omega, posPEF, rotVel);

                //Add the instantaneous velocity due to rotation.
                iauPpp(velPEF, rotVel, retDataVel);

                //Rotate from the PEF into the TEME
                iauRxp(PEF2TEME, retDataVel, retDataVel);
            }
        }
    }
    
    plhs[0]=retMat;
    
    if(nlhs>1) {
        double *elPtr;
        size_t i,j;
        
        plhs[1]=mxCreateDoubleMatrix(3,3,mxREAL);
        elPtr=(double*)mxGetData(plhs[1]);
        
        for (i=0;i<3;i++) {
            for(j=0;j<3;j++) {
                elPtr[i+3*j]=ITRS2TEME[i][j];
            }
        }
    }
}
Example #8
0
File: trxp.c Project: ddj116/gmat
void iauTrxp(double r[3][3], double p[3], double trp[3])
/*
**  - - - - - - - -
**   i a u T r x p
**  - - - - - - - -
**
**  Multiply a p-vector by the transpose of an r-matrix.
**
**  This function is part of the International Astronomical Union's
**  SOFA (Standards Of Fundamental Astronomy) software collection.
**
**  Status:  vector/matrix support function.
**
**  Given:
**     r        double[3][3]   r-matrix
**     p        double[3]      p-vector
**
**  Returned:
**     trp      double[3]      r * p
**
**  Note:
**     It is permissible for p and trp to be the same array.
**
**  Called:
**     iauTr        transpose r-matrix
**     iauRxp       product of r-matrix and p-vector
**
**  This revision:  2008 October 28
**
**  SOFA release 2010-12-01
**
**  Copyright (C) 2010 IAU SOFA Board.  See notes at end.
*/
{
   double tr[3][3];


/* Transpose of matrix r. */
   iauTr(r, tr);

/* Matrix tr * vector p -> vector trp. */
   iauRxp(tr, p, trp);

   return;

/*----------------------------------------------------------------------
**
**  Copyright (C) 2010
**  Standards Of Fundamental Astronomy Board
**  of the International Astronomical Union.
**
**  =====================
**  SOFA Software License
**  =====================
**
**  NOTICE TO USER:
**
**  BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING TERMS AND CONDITIONS
**  WHICH APPLY TO ITS USE.
**
**  1. The Software is owned by the IAU SOFA Board ("SOFA").
**
**  2. Permission is granted to anyone to use the SOFA software for any
**     purpose, including commercial applications, free of charge and
**     without payment of royalties, subject to the conditions and
**     restrictions listed below.
**
**  3. You (the user) may copy and distribute SOFA source code to others,
**     and use and adapt its code and algorithms in your own software,
**     on a world-wide, royalty-free basis.  That portion of your
**     distribution that does not consist of intact and unchanged copies
**     of SOFA source code files is a "derived work" that must comply
**     with the following requirements:
**
**     a) Your work shall be marked or carry a statement that it
**        (i) uses routines and computations derived by you from
**        software provided by SOFA under license to you; and
**        (ii) does not itself constitute software provided by and/or
**        endorsed by SOFA.
**
**     b) The source code of your derived work must contain descriptions
**        of how the derived work is based upon, contains and/or differs
**        from the original SOFA software.
**
**     c) The name(s) of all routine(s) in your derived work shall not
**        include the prefix "iau".
**
**     d) The origin of the SOFA components of your derived work must
**        not be misrepresented;  you must not claim that you wrote the
**        original software, nor file a patent application for SOFA
**        software or algorithms embedded in the SOFA software.
**
**     e) These requirements must be reproduced intact in any source
**        distribution and shall apply to anyone to whom you have
**        granted a further right to modify the source code of your
**        derived work.
**
**     Note that, as originally distributed, the SOFA software is
**     intended to be a definitive implementation of the IAU standards,
**     and consequently third-party modifications are discouraged.  All
**     variations, no matter how minor, must be explicitly marked as
**     such, as explained above.
**
**  4. In any published work or commercial products which includes
**     results achieved by using the SOFA software, you shall
**     acknowledge that the SOFA software was used in obtaining those
**     results.
**
**  5. You shall not cause the SOFA software to be brought into
**     disrepute, either by misuse, or use for inappropriate tasks, or
**     by inappropriate modification.
**
**  6. The SOFA software is provided "as is" and SOFA makes no warranty
**     as to its use or performance.   SOFA does not and cannot warrant
**     the performance or results which the user may obtain by using the
**     SOFA software.  SOFA makes no warranties, express or implied, as
**     to non-infringement of third party rights, merchantability, or
**     fitness for any particular purpose.  In no event will SOFA be
**     liable to the user for any consequential, incidental, or special
**     damages, including any lost profits or lost savings, even if a
**     SOFA representative has been advised of such damages, or for any
**     claim by any third party.
**
**  7. The provision of any version of the SOFA software under the terms
**     and conditions specified herein does not imply that future
**     versions will also be made available under the same terms and
**     conditions.
**
**  Correspondence concerning SOFA software should be addressed as
**  follows:
**
**      By email:  [email protected]
**      By post:   IAU SOFA Center
**                 HM Nautical Almanac Office
**                 UK Hydrographic Office
**                 Admiralty Way, Taunton
**                 Somerset, TA1 2DN
**                 United Kingdom
**
**--------------------------------------------------------------------*/
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    double TT1, TT2, dX, dY, *xVec;
    size_t numRow, numVec;
    mxArray *retMat;
    double *retData;
    double GCRS2CIRS[3][3];
    double CIRS2GCRS[3][3];
    
    if(nrhs<3||nrhs>4){
        mexErrMsgTxt("Wrong number of inputs");
    }
    
    if(nlhs>2) {
        mexErrMsgTxt("Wrong number of outputs.");
    }
    
    checkRealDoubleArray(prhs[0]);
    
    numRow = mxGetM(prhs[0]);
    numVec = mxGetN(prhs[0]);
    
    if(!(numRow==3||numRow==6)) {
        mexErrMsgTxt("The input vector has a bad dimensionality.");
    }

    xVec=(double*)mxGetData(prhs[0]);
    TT1=getDoubleFromMatlab(prhs[1]);
    TT2=getDoubleFromMatlab(prhs[2]);
    
    //If some values from the function getEOP will be needed.
    if(nrhs<4||mxIsEmpty(prhs[3])) {
        mxArray *retVals[2];
        double *dXdY;
        mxArray *JulUTCMATLAB[2];
        double JulUTC[2];
        int retVal;
        
        //Get the time in UTC to look up the parameters by going to TAI and
        //then UTC.
        retVal=iauTttai(TT1, TT2, &JulUTC[0], &JulUTC[1]);
        if(retVal!=0) {
            mexErrMsgTxt("An error occurred computing TAI.");
        }
        retVal=iauTaiutc(JulUTC[0], JulUTC[1], &JulUTC[0], &JulUTC[1]);
        switch(retVal){
            case 1:
                mexWarnMsgTxt("Dubious Date entered.");
                break;
            case -1:
                mexErrMsgTxt("Unacceptable date entered");
                break;
            default:
                break;
        }
        
        JulUTCMATLAB[0]=doubleMat2Matlab(&JulUTC[0],1,1);
        JulUTCMATLAB[1]=doubleMat2Matlab(&JulUTC[1],1,1);

        //Get the Earth orientation parameters for the given date.
        mexCallMATLAB(2,retVals,2,JulUTCMATLAB,"getEOP");
        mxDestroyArray(JulUTCMATLAB[0]);
        mxDestroyArray(JulUTCMATLAB[1]);
        
        //%We do not need the polar motion coordinates.
        mxDestroyArray(retVals[0]);
        
        checkRealDoubleArray(retVals[1]);
        if(mxGetM(retVals[1])!=2||mxGetN(retVals[1])!=1) {
            mxDestroyArray(retVals[1]);
            mexErrMsgTxt("Error using the getEOP function.");
            return;
        }
        
        dXdY=(double*)mxGetData(retVals[1]);
        dX=dXdY[0];
        dY=dXdY[1];
        
        //Free the returned arrays.
        mxDestroyArray(retVals[1]);
    } else {//Get the celestial pole offsets
        size_t dim1, dim2;
        
        checkRealDoubleArray(prhs[4]);
        dim1 = mxGetM(prhs[4]);
        dim2 = mxGetN(prhs[4]);
        
        if((dim1==2&&dim2==1)||(dim1==1&&dim2==2)) {
            double *dXdY=(double*)mxGetData(prhs[4]);
        
            dX=dXdY[0];
            dY=dXdY[1];
        } else {
            mexErrMsgTxt("The celestial pole offsets have the wrong dimensionality.");
            return;
        }
    }
    
    {
    double x, y, s;
        
    //Get the X,Y coordinates of the Celestial Intermediate Pole (CIP) and
    //the Celestial Intermediate Origin (CIO) locator s, using the IAU 2006
    //precession and IAU 2000A nutation models.
    iauXys06a(TT1, TT2, &x, &y, &s);
    
    //Add the CIP offsets.
    x += dX;
    y += dY;
    
    //Get the GCRS-to-CIRS matrix
    iauC2ixys(x, y, s, GCRS2CIRS);
    //To go from the CIRS to the GCRS, we need to use the inverse rotation
    //matrix, which is just the transpose of the rotation matrix.
    iauTr(GCRS2CIRS, CIRS2GCRS);
    }
    
    //Allocate space for the return vectors.
    retMat=mxCreateDoubleMatrix(numRow,numVec,mxREAL);
    retData=(double*)mxGetData(retMat);
    
    {
        size_t curVec;
        for(curVec=0;curVec<numVec;curVec++) {
            //Multiply the position vector with the rotation matrix.
            iauRxp(CIRS2GCRS, xVec+numRow*curVec, retData+numRow*curVec);
            
            //If a velocity vector was given.
            if(numRow>3) {
                double *velCIRS=xVec+numRow*curVec+3;//Velocity in CIRS
                double *retDataVel=retData+numRow*curVec+3;
                
                //Convert velocity from CIRS to GCRS.
                iauRxp(CIRS2GCRS, velCIRS, retDataVel);
            }
        }
    }
    plhs[0]=retMat;
    
    //If the rotation matrix is desired on the output.
    if(nlhs>1) {
        double *elPtr;
        size_t i,j;
        
        plhs[1]=mxCreateDoubleMatrix(3,3,mxREAL);
        elPtr=(double*)mxGetData(plhs[1]);
        
        for (i=0;i<3;i++) {
            for(j=0;j<3;j++) {
                elPtr[i+3*j]=CIRS2GCRS[i][j];
            }
        }
    }
}