int main(void)
{
long idum=(-1);
int j;
float a,b,chi2,q,sa,sb,siga,sigb;
float *x,*y,*dx,*dy,*dz;
x=vector(1,NPT);
y=vector(1,NPT);
dx=vector(1,NPT);
dy=vector(1,NPT);
dz=vector(1,NPT);
for (j=1;j<=NPT;j++) {
dx[j]=0.1+ran1(&idum);
dy[j]=0.1+ran1(&idum);
dz[j]=0.0;
x[j]=10.0+10.0*gasdev(&idum);
y[j]=2.0*x[j]-5.0+dy[j]*gasdev(&idum);
x[j] += dx[j]*gasdev(&idum);
}
printf("Values of a,b,siga,sigb,chi2,q:\n");
printf("Fit with x and y errors gives:\n");
fitexy(x,y,NPT,dx,dy,&a,&b,&siga,&sigb,&chi2,&q);
printf("%11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n\n",
a,b,siga,sigb,chi2,q);
printf("Setting x errors to zero gives:\n");
fitexy(x,y,NPT,dz,dy,&a,&b,&siga,&sigb,&chi2,&q);
printf("%11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n",
a,b,siga,sigb,chi2,q);
printf("...to be compared with fit result:\n");
fit(x,y,NPT,dy,1,&a,&b,&siga,&sigb,&chi2,&q);
printf("%11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n\n",
a,b,siga,sigb,chi2,q);
printf("Setting y errors to zero gives:\n");
fitexy(x,y,NPT,dx,dz,&a,&b,&siga,&sigb,&chi2,&q);
printf("%11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n",
a,b,siga,sigb,chi2,q);
printf("...to be compared with fit result:\n");
fit(y,x,NPT,dx,1,&a,&b,&siga,&sigb,&chi2,&q);
sa=sqrt(siga*siga+SQR(sigb*(a/b)))/b;
sb=sigb/(b*b);
printf("%11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n",
-a/b,1.0/b,sa,sb,chi2,q);
free_vector(dz,1,NPT);
free_vector(dy,1,NPT);
free_vector(dx,1,NPT);
free_vector(y,1,NPT);
free_vector(x,1,NPT);
return 0;
}
do_line()
{
real *x, *y, *dx, *dy, *dz;
int i,j, mwt;
real chi2,q,siga,sigb, sigma, d, sa, sb;
real cov00, cov01, cov11, sumsq;
real r, prob, z;
void fit(), pearsn();
if (nxcol < 1) error("nxcol=%d",nxcol);
if (nycol < 1) error("nycol=%d",nycol);
x = xcol[0].dat;
y = ycol[0].dat;
dx = (dxcolnr>0 ? dxcol.dat : NULL);
dy = (dycolnr>0 ? dycol.dat : NULL);
#if HAVE_GSL
if (dx) error("Cannot use GSL with errors in X column");
gsl_fit_linear (x, 1, y, 1, npt, &b, &a,
&cov00, &cov01, &cov11, &sumsq);
printf("y=ax+b: a=%g b=%g cov00,01,11=%g %g %g sumsq=%g\n",
a,b, cov00,cov01,cov11, sumsq);
if (dy) {
for (i=0; i<npt; i++)
dy[i] = 1/(dy[i]*dy[i]);
gsl_fit_wlinear (x, 1, dy, 1, y, 1, npt, &b, &a,
&cov00, &cov01, &cov11, &chi2);
printf("y=ax+b: a=%g b=%g cov00,01,11=%g %g %g chi^2=%g\n",
a,b, cov00,cov01,cov11, chi2);
}
#else
if (dx) {
#if defined(TESTNR)
warning("new FITEXY method");
dz = (real *) allocate(npt*sizeof(real));
for (i=0; i<npt; i++) dz[i] = 0.0;
fitexy(x,y,npt,dx,dy,&b,&a,&sigb,&siga,&chi2,&q);
printf("fitexy(x,y,dx,dy) a=%g b=%g %g %g\n",b,a,sigb,siga);
fitexy(x,y,npt,dz,dy,&a,&b,&siga,&sigb,&chi2,&q);
printf("fitexy(x,y, 0,dy) a=%g b=%g %g %g\n",a,b,siga,sigb);
fitexy(x,y,npt,dx,dz,&a,&b,&siga,&sigb,&chi2,&q);
printf("fitexy(x,y,dx, 0) a=%g b=%g %g %g\n",a,b,siga,sigb);
fit (x,y,npt,dy, 1,&a,&b,&siga,&sigb,&chi2,&q);
printf("fit (x,y, 0,dy) a=%g b=%g %g %g\n",a,b,siga,sigb);
fit (y,x,npt,dx, 1,&a,&b,&siga,&sigb,&chi2,&q);
printf("fit (y,x, 0,dx) a=%g b=%g %g %g\n",a,b,siga,sigb);
sa=sqrt(siga*siga+sqr(sigb*(a/b)))/b;
sb=sigb/(b*b);
printf("FITEXY: %11.6f %11.6f %11.6f %11.6f %11.6f %11.6f\n",
-a/b,1.0/b,sa,sb,chi2,q);
#elif defined(TESTMP)
struct vars_struct v; /* private data for mpfit() */
int status;
mp_result result;
double p[2] = {1.0, 1.0};
double perror[2];
warning("MPFIT method; mode mpfit=%d",mpfit_mode);
bzero(&result,sizeof(result));
result.xerror = perror;
v.x = xcol[0].dat;
v.y = ycol[0].dat;
v.ex = dxcol.dat;
v.ey = dycol.dat;
v.mode = mpfit_mode;
status = mpfit(linfitex, npt, 2, p, 0, 0, (void *) &v, &result);
dprintf(1,"*** mpfit status = %d\n", status);
printf(" CHI-SQUARE = %f (%d DOF)\n",
result.bestnorm, result.nfunc-result.nfree);
printf(" NPAR = %d\n", result.npar);
printf(" NFREE = %d\n", result.nfree);
printf(" NPEGGED = %d\n", result.npegged);
printf(" NITER = %d\n", result.niter);
printf(" NFEV = %d\n", result.nfev);
printf("\n");
for (i=0; i<result.npar; i++) {
printf(" P[%d] = %f +/- %f\n",
i, p[i], result.xerror[i]);
}
#else
error("no dycol= implemented yet");
#endif
} else {
for(mwt=0;mwt<=1;mwt++) {
#if 1
if (mwt>0 && nsigma>0) {
fit(x,y,npt,dy,0,&b,&a,&sigb,&siga,&chi2,&q);
} else {
if (mwt>0 && dycolnr==0)
continue;
fit(x,y,npt,dy,mwt,&b,&a,&sigb,&siga,&chi2,&q);
}
#else
if (mwt==0)
fit(x,y,npt,dy,mwt,&b,&a,&sigb,&siga,&chi2,&q);
else
myfit(x,y,npt,dy,mwt,&b,&a,&sigb,&siga,&chi2,&q);
#endif
dprintf(2,"\n");
dprintf (1,"Fit: y=ax+b\n");
if (mwt == 0)
dprintf(1,"Ignoring standard deviations\n");
else
dprintf(1,"Including standard deviation\n");
printf("%12s %9.6f %18s %9.6f \n",
"a = ",a,"uncertainty:",siga);
printf("%12s %9.6f %18s %9.6f \n",
"b = ",b,"uncertainty:",sigb);
printf("%12s %9.6f %18s %9.6f \n",
"x0 = ",-b/a,"uncertainty:",sqrt(sqr(sigb/a)+sqr(siga*b/(a*a))));
printf("%12s %9.6f %18s %9.6f \n",
"y0 = ",b,"uncertainty:",sigb);
printf("%19s %14.6f \n","chi-squared: ",chi2);
printf("%23s %10.6f %s\n","goodness-of-fit: ",q,
q==1 ? "(no Y errors supplied [dycol=])" : "");
pearsn(x, y, npt, &r, &prob, &z);
printf("%9s %g\n","r: ",r);
printf("%12s %g\n","prob: ",prob);
printf("%9s %g\n","z: ",z);
if (mwt==0 && nsigma>0) {
sigma = 0.0;
for(i=0; i<npt; i++)
sigma += sqr(y[i] - a*x[i] - b);
sigma /= (real) npt;
sigma = nsigma * sqrt(sigma); /* critical distance */
for(i=0, j=0; i<npt; i++) { /* loop over points */
d = ABS(y[i] - a*x[i] - b);
if (d > sigma) continue;
x[j] = x[i]; /* shift them over */
y[j] = y[i];
if (dy) dy[j] = dy[i];
j++;
}
dprintf(0,"%d/%d points outside %g*sigma (%g)\n",
npt-j,npt,nsigma,sigma);
npt = j;
}
} /* mwt */
} /* dxcol */
if (outstr) write_data(outstr);
#endif
}
