/*
 * highly inefficient computation of the imaginary part of complex 
 * conjugate eigenvalues of a 3x3 non-symmetric matrix
 */ 
double
gage_imaginary_part_eigenvalues( gage_t *M ) {
    double A, B, C, scale, frob, m[9], _eval[3];
    double beta, gamma;
    int roots;

    frob = ELL_3M_FROB(M);
    scale = frob > 10 ? 10.0/frob : 1.0;
    ELL_3M_SCALE(m, scale, M);
    /* 
    ** from gordon with mathematica; these are the coefficients of the
    ** cubic polynomial in x: det(x*I - M).  The full cubic is
    ** x^3 + A*x^2 + B*x + C.
    */
    A = -m[0] - m[4] - m[8];
    B = m[0]*m[4] - m[3]*m[1] 
        + m[0]*m[8] - m[6]*m[2] 
        + m[4]*m[8] - m[7]*m[5];
    C = (m[6]*m[4] - m[3]*m[7])*m[2]
        + (m[0]*m[7] - m[6]*m[1])*m[5]
        + (m[3]*m[1] - m[0]*m[4])*m[8];
    roots = ell_cubic(_eval, A, B, C, AIR_TRUE);
    if ( roots != ell_cubic_root_single )
        return 0.;

    /* 2 complex conjuguate eigenvalues */
    beta = A + _eval[0];
    gamma = -C/_eval[0];
    return sqrt( 4.*gamma - beta*beta );
}
示例#2
0
文件: eigen.c 项目: BRAINSia/teem
/*
******** ell_3m_eigenvalues_d()
**
** finds eigenvalues of given matrix.
**
** returns information about the roots according to ellCubeRoot enum,
** see header for ellCubic for details.
**
** given matrix is NOT modified
**
** This does NOT use biff
**
** Doing the frobenius normalization proved successfull in avoiding the
** the creating of NaN eigenvalues when the coefficients of the matrix
** were really large (> 50000).  Also, when the matrix norm was really
** small, the comparison to "epsilon" in ell_cubic mistook three separate
** roots for a single and a double, with this matrix in particular:
**  1.7421892  0.0137642  0.0152975
**  0.0137642  1.7565432 -0.0062296
**  0.0152975 -0.0062296  1.7700019
** (actually, this is prior to tenEigensolve's isotropic removal)
**
** HEY: tenEigensolve_d and tenEigensolve_f start by removing the
** isotropic part of the tensor.  It may be that that smarts should
** be migrated here, but GLK is uncertain how it would change the
** handling of non-symmetric matrices.
*/
int
ell_3m_eigenvalues_d(double _eval[3], const double _m[9], const int newton) {
  double A, B, C, scale, frob, m[9], eval[3];
  int roots;

  frob = ELL_3M_FROB(_m);
  scale = frob ? 1.0/frob : 1.0;
  ELL_3M_SCALE(m, scale, _m);
  /*
  printf("!%s: m = %g %g %g; %g %g %g; %g %g %g\n", "ell_3m_eigenvalues_d",
         m[0], m[1], m[2], m[3], m[4], m[5], m[6], m[7], m[8]);
  */
  /*
  ** from gordon with mathematica; these are the coefficients of the
  ** cubic polynomial in x: det(x*I - M).  The full cubic is
  ** x^3 + A*x^2 + B*x + C.
  */
  A = -m[0] - m[4] - m[8];
  B = m[0]*m[4] - m[3]*m[1]
    + m[0]*m[8] - m[6]*m[2]
    + m[4]*m[8] - m[7]*m[5];
  C = (m[6]*m[4] - m[3]*m[7])*m[2]
    + (m[0]*m[7] - m[6]*m[1])*m[5]
    + (m[3]*m[1] - m[0]*m[4])*m[8];
  /*
  printf("!%s: A B C = %g %g %g\n", "ell_3m_eigenvalues_d", A, B, C);
  */
  roots = ell_cubic(eval, A, B, C, newton);
  /* no longer need to sort here */
  ELL_3V_SCALE(_eval, 1.0/scale, eval);
  return roots;
}
示例#3
0
文件: tsoid.c 项目: BRAINSia/teem
static void
scalingMatrix(double mat[9], double vec[3], double scl) {
  double dir[3], tmp[9], len;

  ELL_3V_NORM(dir, vec, len);
  ELL_3MV_OUTER(tmp, dir, dir);
  ELL_3M_SCALE(tmp, scl-1, tmp);
  ELL_3M_IDENTITY_SET(mat);
  ELL_3M_ADD2(mat, mat, tmp);
  return;
}
示例#4
0
int
main(int argc, const char *argv[]) {
  const char *me;
  char *err, *outS;
  double scale[3], matA[9], matB[9], matC[9], sval[3], uu[9], vv[9];
  float matAf[9], matBf[16];
  float p[3], q[4], mR[9], len, gamma;
  float os, vs, rad, AB[2], ten[7], view[3];
  hestOpt *hopt=NULL;
  airArray *mop;
  limnObject *obj;
  limnLook *look; int lookRod, lookSoid;
  int partIdx=-1; /* sssh */
  int res, sphere;
  FILE *file;

  me = argv[0];
  hestOptAdd(&hopt, "sc", "scalings", airTypeDouble, 3, 3, scale, "1 1 1",
             "axis-aligned scaling to do on ellipsoid");
  hestOptAdd(&hopt, "AB", "A, B exponents", airTypeFloat, 2, 2, AB, "nan nan",
             "Directly set the A, B parameters to the superquadric surface, "
             "over-riding the default behavior of determining them from the "
             "scalings \"-sc\" as superquadric tensor glyphs");
  hestOptAdd(&hopt, "os", "over-all scaling", airTypeFloat, 1, 1, &os, "1",
             "over-all scaling (multiplied by scalings)");
  hestOptAdd(&hopt, "vs", "over-all scaling", airTypeFloat, 1, 1, &vs, "1",
             "scaling along view-direction (to show off bas-relief "
             "ambibuity of ellipsoids versus superquads)");
  hestOptAdd(&hopt, "fr", "from (eye) point", airTypeFloat, 3, 3, &view,
             "4 4 4", "eye point, needed for non-unity \"-vs\"");
  hestOptAdd(&hopt, "gamma", "superquad sharpness", airTypeFloat, 1, 1,
             &gamma, "0",
             "how much to sharpen edges as a "
             "function of differences between eigenvalues");
  hestOptAdd(&hopt, "sphere", NULL, airTypeInt, 0, 0, &sphere, NULL,
             "use a sphere instead of a superquadric");
  hestOptAdd(&hopt, "p", "x y z", airTypeFloat, 3, 3, p, "0 0 0",
             "location in quaternion quotient space");
  hestOptAdd(&hopt, "r", "radius", airTypeFloat, 1, 1, &rad, "0.015",
             "black axis cylinder radius (or 0.0 to not drawn these)");
  hestOptAdd(&hopt, "res", "resolution", airTypeInt, 1, 1, &res, "25",
             "tesselation resolution for both glyph and axis cylinders");
  hestOptAdd(&hopt, "o", "output OFF", airTypeString, 1, 1, &outS, "out.off",
             "output file to save OFF into");
  hestParseOrDie(hopt, argc-1, argv+1, NULL,
                 me, info, AIR_TRUE, AIR_TRUE, AIR_TRUE);
  mop = airMopNew();
  airMopAdd(mop, hopt, (airMopper)hestOptFree, airMopAlways);
  airMopAdd(mop, hopt, (airMopper)hestParseFree, airMopAlways);

  obj = limnObjectNew(1000, AIR_TRUE);
  airMopAdd(mop, obj, (airMopper)limnObjectNix, airMopAlways);

  /* create limnLooks for ellipsoid and for rods */
  lookSoid = limnObjectLookAdd(obj);
  look = obj->look + lookSoid;
  ELL_4V_SET(look->rgba, 1, 1, 1, 1);
  ELL_3V_SET(look->kads, 0.2, 0.8, 0);
  look->spow = 0;
  lookRod = limnObjectLookAdd(obj);
  look = obj->look + lookRod;
  ELL_4V_SET(look->rgba, 0, 0, 0, 1);
  ELL_3V_SET(look->kads, 1, 0, 0);
  look->spow = 0;

  ELL_3M_IDENTITY_SET(matA);
  ELL_3V_SCALE(scale, os, scale);
  ELL_3M_SCALE_SET(matB, scale[0], scale[1], scale[2]);
  ell_3m_post_mul_d(matA, matB);
  if (1 != vs) {
    ELL_3V_NORM(view, view, len);
    if (!len) {
      /* HEY: perhaps do more diplomatic error message here */
      fprintf(stderr, "%s: stupido!\n", me);
      exit(1);
    }
    ELL_3MV_OUTER(matB, view, view);
    ELL_3M_SCALE(matB, vs-1, matB);
    ELL_3M_IDENTITY_SET(matC);
    ELL_3M_ADD2(matB, matC, matB);
    ell_3m_post_mul_d(matA, matB);
  }
  ell_3m_svd_d(uu, sval, vv, matA, AIR_TRUE);

  /*
  fprintf(stderr, "%s: ____________________________________\n", me);
  fprintf(stderr, "%s: mat = \n", me);
  ell_3m_print_d(stderr, matA);
  fprintf(stderr, "%s: uu = \n", me);
  ell_3m_print_d(stderr, uu);
  ELL_3M_TRANSPOSE(matC, uu);
  ELL_3M_MUL(matB, uu, matC);
  fprintf(stderr, "%s: uu * uu^T = \n", me);
  ell_3m_print_d(stderr, matB);
  fprintf(stderr, "%s: sval = %g %g %g\n", me, sval[0], sval[1], sval[2]);
  fprintf(stderr, "%s: vv = \n", me);
  ell_3m_print_d(stderr, vv);
  ELL_3M_MUL(matB, vv, vv);
  fprintf(stderr, "%s: vv * vv^T = \n", me);
  ELL_3M_TRANSPOSE(matC, vv);
  ELL_3M_MUL(matB, vv, matC);
  ell_3m_print_d(stderr, matB);
  ELL_3M_IDENTITY_SET(matA);
  ell_3m_pre_mul_d(matA, uu);
  ELL_3M_SCALE_SET(matB, sval[0], sval[1], sval[2]);
  ell_3m_pre_mul_d(matA, matB);
  ell_3m_pre_mul_d(matA, vv);
  fprintf(stderr, "%s: uu * diag(sval) * vv = \n", me);
  ell_3m_print_d(stderr, matA);
  fprintf(stderr, "%s: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n", me);
  */

  ELL_3M_IDENTITY_SET(matA);
  ell_3m_pre_mul_d(matA, uu);
  ELL_3M_SCALE_SET(matB, sval[0], sval[1], sval[2]);
  ell_3m_pre_mul_d(matA, matB);
  ELL_3M_TRANSPOSE(matB, uu);
  ell_3m_pre_mul_d(matA, matB);
  TEN_M2T(ten, matA);

  partIdx = soidDoit(obj, lookSoid,
                     sphere, gamma, res,
                     (AIR_EXISTS(AB[0]) && AIR_EXISTS(AB[1])) ? AB : NULL,
                     ten);

  ELL_4V_SET(q, 1, p[0], p[1], p[2]);
  ELL_4V_NORM(q, q, len);
  ell_q_to_3m_f(mR, q);
  ELL_43M_INSET(matBf, mR);
  limnObjectPartTransform(obj, partIdx, matBf);

  if (rad) {
    partIdx = limnObjectCylinderAdd(obj, lookRod, 0, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, (1-scale[0])/2, rad, rad);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, (1+scale[0])/2, 0.0, 0.0);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);

    partIdx = limnObjectCylinderAdd(obj, lookRod, 0, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, (1-scale[0])/2, rad, rad);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, -(1+scale[0])/2, 0.0, 0.0);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);

    partIdx = limnObjectCylinderAdd(obj, lookRod, 1, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, rad, (1-scale[1])/2, rad);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, 0.0, (1+scale[1])/2, 0.0);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);

    partIdx = limnObjectCylinderAdd(obj, lookRod, 1, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, rad, (1-scale[1])/2, rad);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, 0.0, -(1+scale[1])/2, 0.0);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);

    partIdx = limnObjectCylinderAdd(obj, lookRod, 2, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, rad, rad, (1-scale[2])/2);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, 0.0, 0.0, (1+scale[2])/2);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);

    partIdx = limnObjectCylinderAdd(obj, lookRod, 2, res);
    ELL_4M_IDENTITY_SET(matAf);
    ELL_4M_SCALE_SET(matBf, rad, rad, (1-scale[2])/2);
    ell_4m_post_mul_f(matAf, matBf);
    ELL_4M_TRANSLATE_SET(matBf, 0.0, 0.0, -(1+scale[2])/2);
    ell_4m_post_mul_f(matAf, matBf);
    limnObjectPartTransform(obj, partIdx, matAf);
  }

  file = airFopen(outS, stdout, "w");
  airMopAdd(mop, file, (airMopper)airFclose, airMopAlways);

  if (limnObjectWriteOFF(file, obj)) {
    airMopAdd(mop, err = biffGetDone(LIMN), airFree, airMopAlways);
    fprintf(stderr, "%s: trouble:\n%s\n", me, err);
    airMopError(mop); return 1;
  }

  airMopOkay(mop);
  return 0;
}
示例#5
0
void
_gageSclAnswer (gageContext *ctx, gagePerVolume *pvl) {
  char me[]="_gageSclAnswer";
  double gmag=0, *hess, *norm, *gvec, *gten, *k1, *k2, curv=0, 
    sHess[9]={0,0,0,0,0,0,0,0,0};
  double tmpMat[9], tmpVec[3], hevec[9], heval[3];
  double len, gp1[3], gp2[3], *nPerp, ncTen[9], nProj[9]={0,0,0,0,0,0,0,0,0};
  double alpha = 0.5;
  double beta = 0.5;
  double gamma = 5;
  double cc = 1e-6;
#define FD_MEDIAN_MAX 16
  int fd, nidx, xi, yi, zi;
  double *fw, iv3wght[2*FD_MEDIAN_MAX*FD_MEDIAN_MAX*FD_MEDIAN_MAX],
    wghtSum, wght;

  /* convenience pointers for work below */
  hess = pvl->directAnswer[gageSclHessian];
  gvec = pvl->directAnswer[gageSclGradVec];
  norm = pvl->directAnswer[gageSclNormal];
  nPerp = pvl->directAnswer[gageSclNPerp];
  gten = pvl->directAnswer[gageSclGeomTens];
  k1 = pvl->directAnswer[gageSclK1];
  k2 = pvl->directAnswer[gageSclK2];
  
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclValue)) {
    /* done if doV */
    if (ctx->verbose) {
      fprintf(stderr, "%s: val = % 15.7f\n", me, 
              (double)(pvl->directAnswer[gageSclValue][0]));
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclGradVec)) {
    /* done if doD1 */
    if (ctx->verbose) {
      fprintf(stderr, "%s: gvec = ", me);
      ell_3v_print_d(stderr, gvec);
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclGradMag)) {
    /* this is the true value of gradient magnitude */
    gmag = pvl->directAnswer[gageSclGradMag][0] = sqrt(ELL_3V_DOT(gvec, gvec));
  }

  /* NB: it would seem that gageParmGradMagMin is completely ignored ... */

  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclNormal)) {
    if (gmag) {
      ELL_3V_SCALE(norm, 1/gmag, gvec);
      /* polishing ... 
      len = sqrt(ELL_3V_DOT(norm, norm));
      ELL_3V_SCALE(norm, 1/len, norm);
      */
    } else {
      ELL_3V_COPY(norm, gageZeroNormal);
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclNPerp)) {
    /* nPerp = I - outer(norm, norm) */
    /* NB: this sets both nPerp and nProj */
    ELL_3MV_OUTER(nProj, norm, norm);
    ELL_3M_SCALE(nPerp, -1, nProj);
    nPerp[0] += 1;
    nPerp[4] += 1;
    nPerp[8] += 1;
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessian)) {
    /* done if doD2 */
    if (ctx->verbose) {
      fprintf(stderr, "%s: hess = \n", me);
      ell_3m_print_d(stderr, hess);
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclLaplacian)) {
    pvl->directAnswer[gageSclLaplacian][0] = hess[0] + hess[4] + hess[8];
    if (ctx->verbose) {
      fprintf(stderr, "%s: lapl = %g + %g + %g  = %g\n", me,
              hess[0], hess[4], hess[8], 
              pvl->directAnswer[gageSclLaplacian][0]);
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessFrob)) {
    pvl->directAnswer[gageSclHessFrob][0] = ELL_3M_FROB(hess);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessEval)) {
    /* HEY: look at the return value for root multiplicity? */
    ell_3m_eigensolve_d(heval, hevec, hess, AIR_TRUE);
    ELL_3V_COPY(pvl->directAnswer[gageSclHessEval], heval);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessEvec)) {
    ELL_3M_COPY(pvl->directAnswer[gageSclHessEvec], hevec);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessRidgeness)) {
    double A, B, S;
    if (heval[1] >0 || heval[2]>0) {
      pvl->directAnswer[gageSclHessRidgeness][0] = 0;
    }
    else if (AIR_ABS(heval[1])<1e-10 || AIR_ABS(heval[2])<1e-10) {
      pvl->directAnswer[gageSclHessRidgeness][0] = 0;
    }
    else {
      double *ans;
      A = AIR_ABS(heval[1])/AIR_ABS(heval[2]);
      B = AIR_ABS(heval[0])/sqrt(AIR_ABS(heval[1]*heval[2]));
      S = sqrt(heval[0]*heval[0] + heval[1]*heval[1] + heval[2]*heval[2]);
      ans = pvl->directAnswer[gageSclHessRidgeness];
      ans[0] = (1-exp(-A*A/(2*alpha*alpha))) *
        exp(-B*B/(2*beta*beta)) *
        (1-exp(-S*S/(2*gamma*gamma))) *
        exp(-2*cc*cc/(AIR_ABS(heval[1])*heval[2]*heval[2]));
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessValleyness)) {
    double A, B, S;
    if (heval[0] <0 || heval[1]<0) {
      pvl->directAnswer[gageSclHessValleyness][0] = 0;
    }
    else if (AIR_ABS(heval[0])<1e-10 || AIR_ABS(heval[1])<1e-10) {
      pvl->directAnswer[gageSclHessValleyness][0] = 0;
    }
    else {
      double *ans;
      A = AIR_ABS(heval[1])/AIR_ABS(heval[0]);
      B = AIR_ABS(heval[2])/sqrt(AIR_ABS(heval[1]*heval[0]));
      S = sqrt(heval[0]*heval[0] + heval[1]*heval[1] + heval[2]*heval[2]);
      ans = pvl->directAnswer[gageSclHessValleyness];
      ans[0] = (1-exp(-A*A/(2*alpha*alpha))) *
        exp(-B*B/(2*beta*beta)) *
        (1-exp(-S*S/(2*gamma*gamma))) *
        exp(-2*cc*cc/(AIR_ABS(heval[1])*heval[0]*heval[0]));
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclHessMode)) {
    pvl->directAnswer[gageSclHessMode][0] = airMode3_d(heval);
  }

  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageScl2ndDD)) {
    ELL_3MV_MUL(tmpVec, hess, norm);
    pvl->directAnswer[gageScl2ndDD][0] = ELL_3V_DOT(norm, tmpVec);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclGeomTens)) {
    if (gmag > ctx->parm.gradMagCurvMin) {
      /* parm.curvNormalSide applied here to determine the sense of the
         normal when doing all curvature calculations */
      ELL_3M_SCALE(sHess, -(ctx->parm.curvNormalSide)/gmag, hess);
      
      /* gten = nPerp * sHess * nPerp */
      ELL_3M_MUL(tmpMat, sHess, nPerp);
      ELL_3M_MUL(gten, nPerp, tmpMat);

      if (ctx->verbose) {
        fprintf(stderr, "%s: gten: \n", me);
        ell_3m_print_d(stderr, gten);
        ELL_3MV_MUL(tmpVec, gten, norm);
        len = ELL_3V_LEN(tmpVec);
        fprintf(stderr, "%s: should be small: %30.15f\n", me, (double)len);
        ell_3v_perp_d(gp1, norm);
        ELL_3MV_MUL(tmpVec, gten, gp1);
        len = ELL_3V_LEN(tmpVec);
        fprintf(stderr, "%s: should be bigger: %30.15f\n", me, (double)len);
        ELL_3V_CROSS(gp2, gp1, norm);
        ELL_3MV_MUL(tmpVec, gten, gp2);
        len = ELL_3V_LEN(tmpVec);
        fprintf(stderr, "%s: should (also) be bigger: %30.15f\n",
                me, (double)len);
      }
    } else {
      ELL_3M_ZERO_SET(gten);
    }
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclTotalCurv)) {
    curv = pvl->directAnswer[gageSclTotalCurv][0] = ELL_3M_FROB(gten);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclShapeTrace)) {
    pvl->directAnswer[gageSclShapeTrace][0] = (curv
                                               ? ELL_3M_TRACE(gten)/curv
                                               : 0);
  }
  if ( (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclK1)) ||
       (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclK2)) ){
    double T, N, D;
    T = ELL_3M_TRACE(gten);
    N = curv;
    D = 2*N*N - T*T;
    /*
    if (D < -0.0000001) {
      fprintf(stderr, "%s: %g %g\n", me, T, N);
      fprintf(stderr, "%s: !!! D curv determinant % 22.10f < 0.0\n", me, D);
      fprintf(stderr, "%s: gten: \n", me);
      ell_3m_print_d(stderr, gten);
    }
    */
    D = AIR_MAX(D, 0);
    D = sqrt(D);
    k1[0] = 0.5*(T + D);
    k2[0] = 0.5*(T - D);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclMeanCurv)) {
    pvl->directAnswer[gageSclMeanCurv][0] = (*k1 + *k2)/2;
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclGaussCurv)) {
    pvl->directAnswer[gageSclGaussCurv][0] = (*k1)*(*k2);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query,  gageSclShapeIndex)) {
    pvl->directAnswer[gageSclShapeIndex][0] = 
      -(2/AIR_PI)*atan2(*k1 + *k2, *k1 - *k2);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclCurvDir1)) {
    /* HEY: this only works when K1, K2, 0 are all well mutually distinct,
       since these are the eigenvalues of the geometry tensor, and this
       code assumes that the eigenspaces are all one-dimensional */
    ELL_3M_COPY(tmpMat, gten);
    ELL_3M_DIAG_SET(tmpMat, gten[0] - *k1, gten[4]- *k1, gten[8] - *k1);
    ell_3m_1d_nullspace_d(tmpVec, tmpMat);
    ELL_3V_COPY(pvl->directAnswer[gageSclCurvDir1], tmpVec);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclCurvDir2)) {
    /* HEY: this only works when K1, K2, 0 are all well mutually distinct,
       since these are the eigenvalues of the geometry tensor, and this
       code assumes that the eigenspaces are all one-dimensional */
    ELL_3M_COPY(tmpMat, gten);
    ELL_3M_DIAG_SET(tmpMat, gten[0] - *k2, gten[4] - *k2, gten[8] - *k2);
    ell_3m_1d_nullspace_d(tmpVec, tmpMat);
    ELL_3V_COPY(pvl->directAnswer[gageSclCurvDir2], tmpVec);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclFlowlineCurv)) {
    if (gmag >= ctx->parm.gradMagCurvMin) {
      /* because of the gageSclGeomTens prerequisite, sHess, nPerp, and
         nProj are all already set */
      /* ncTen = nPerp * sHess * nProj */
      ELL_3M_MUL(tmpMat, sHess, nProj);
      ELL_3M_MUL(ncTen, nPerp, tmpMat);
    } else {
      ELL_3M_ZERO_SET(ncTen);
    }
    /* there used to be a wrong extra sqrt() here */
    pvl->directAnswer[gageSclFlowlineCurv][0] = ELL_3M_FROB(ncTen);
  }
  if (GAGE_QUERY_ITEM_TEST(pvl->query, gageSclMedian)) {
    /* this item is currently a complete oddball in that it does not
       benefit from anything done in the "filter" stage, which is in
       fact a waste of time if the query consists only  of this item */
    fd = 2*ctx->radius;
    if (fd > FD_MEDIAN_MAX) {
      fprintf(stderr, "%s: PANIC: current filter diameter = %d "
              "> FD_MEDIAN_MAX = %d\n", me, fd, FD_MEDIAN_MAX);
      exit(1);
    }
    fw = ctx->fw + fd*3*gageKernel00;
    /* HEY: this needs some optimization help */
    wghtSum = 0;
    nidx = 0;
    for (xi=0; xi<fd; xi++) {
      for (yi=0; yi<fd; yi++) {
        for (zi=0; zi<fd; zi++) {
          iv3wght[0 + 2*nidx] = pvl->iv3[nidx];
          iv3wght[1 + 2*nidx] = fw[xi + 0*fd]*fw[yi + 1*fd]*fw[zi + 2*fd];
          wghtSum += iv3wght[1 + 2*nidx];
          nidx++;
        }
      }
    }
    qsort(iv3wght, fd*fd*fd, 2*sizeof(double), nrrdValCompare[nrrdTypeDouble]);
    wght = 0;
    for (nidx=0; nidx<fd*fd*fd; nidx++) {
      wght += iv3wght[1 + 2*nidx];
      if (wght > wghtSum/2) {
        break;
      }
    }
    pvl->directAnswer[gageSclMedian][0] = iv3wght[0 + 2*nidx];
  }
  return;
}