int ifft2d (CmplxArray *z) {
/* argument:
CmplxArray *z io: complex array
*/
CmplxArray scr; /* scratch space for FT of columns */
int i, j; /* loop indexes */
int nx, ny; /* image size */
int status;
nx = z->nx;
ny = z->ny;
/* Allocate a 1-D array for a column. */
InitCmplxArray (&scr);
if ((status = AllocCmplxArray (&scr, ny, 1)))
return (status);
for (j = 0; j < ny; j++) /* transform each line */
CFFTB (&nx, &(RPIX2D(z,0,j)), z->workx);
for (i = 0; i < nx; i++) { /* transform each column */
for (j = 0; j < ny; j++) {
RPIX1D (&scr, j) = RPIX2D (z, i, j);
IPIX1D (&scr, j) = IPIX2D (z, i, j);
}
CFFTB (&scr.nx, scr.data, scr.workx);
for (j = 0; j < ny; j++) {
RPIX2D (z, i, j) = RPIX1D (&scr, j) / (nx * ny);
IPIX2D (z, i, j) = IPIX1D (&scr, j) / (nx * ny);
}
}
FreeCmplxArray (&scr);
return (0);
}
static int MakeFT (Image *iso, Image *psf, ScatterFunctions *scf,
CmplxArray *ft, CmplxArray *fto) {
/* arguments
Image *iso; i: isotropic halo function (1024 x 1024)
Image *psf; i: telescope PSF for the aperture (normalized)
ScatterFunctions *scf; i: scattering functions
CmplxArray *ft; o: FT
CmplxArray *fto; o: object (central 11 X 11) FT
*/
CmplxArray ziso, zpsf;
float *hold;
int i, j, k, i1, i2, j1, j2, ki, kj, kk;
int ki1, ki2, kj1, kj2;
int status, wsize;
int FFTConvolve (CmplxArray *, CmplxArray *);
/* Initialize complex arrays. */
InitCmplxArray (&ziso);
InitCmplxArray (&zpsf);
/* Copy real into complex arrays. PSF must be copied into
larger array so its size matches the halo array size.
*/
if ((status = AllocCmplxArray (&ziso, iso->nx, iso->ny)))
return (status);
for (j = 1; j < iso->ny - 1; j++) {
for (i = 1; i < iso->nx - 1; i++)
RPIX2D (&ziso, i, j) = PPIX (iso, i-1, j-1);
}
if ((status = AllocCmplxArray (&zpsf, iso->nx, iso->ny)))
return (status);
/* The following code only works when both axis are simultaneously
either even or odd-sized. Half-pixel shifting uses linear interp.
(Is that comment correct?)
*/
if (psf->nx <= iso->nx) {
/* this is the normal case */
i1 = (iso->nx - psf->nx) / 2;
i2 = i1 + psf->nx;
ki1 = 0;
ki2 = psf->nx;
} else {
i1 = 0;
i2 = iso->nx;
ki1 = (psf->nx - iso->nx) / 2;
ki2 = ki1 + iso->nx;
}
if (psf->ny <= iso->ny) {
/* this is the normal case, i.e. a small slit */
j1 = (iso->ny - psf->ny) / 2;
j2 = j1 + psf->ny;
kj1 = 0;
kj2 = psf->ny;
} else {
/* long slit, greater than about 29 arcsec */
j1 = 0;
j2 = iso->ny;
kj1 = (psf->ny - iso->ny) / 2;
kj2 = kj1 + iso->ny;
}
/* xxx ...
if ((i1 % 2) == 0) {
... xxx */
/* copy psf into zpsf */
for (j = j1, kj = kj1; j < j2 && kj < kj2; j++, kj++) {
for (i = i1, ki = ki1; i < i2 && ki < ki2; i++, ki++)
RPIX2D (&zpsf, i, j) = PPIX (psf, ki, kj);
}
/* xxx ...
} else {
for (j = j1, kj = 1; j < j2 - 1; j++, kj++) {
for (i = i1, ki = 1; i < i2 - 1; i++, ki++) {
RPIX2D (&zpsf, i, j) = (PPIX (psf, ki, kj) +
PPIX (psf, ki-1, kj) +
PPIX (psf, ki, kj-1) +
PPIX (psf, ki-1, kj-1)) / 4.0;
}
}
}
... xxx */
/* Convolve halo with telescope PSF. */
if ((status = FFTConvolve (&zpsf, &ziso)))
return (status);
/* Now convolve column-by-column with x-disp scattering function. */
for (i = 0; i < iso->nx; i++) {
hold = (float *) calloc (iso->ny, sizeof (float));
if (hold == NULL)
return (OUT_OF_MEMORY);
for (j = 0; j < iso->ny; j++) {
kk = j - scf->nxdisp / 2;
for (k = 0; k <scf->nxdisp; k++, kk++) {
kk = (kk < 0) ? 0 : kk;
kk = (kk >= iso->ny) ? iso->ny - 1 : kk;
hold[j] += RPIX2D (&zpsf, i, kk) * scf->xdisp[k];
}
}
for (j = 0; j < iso->ny; j++)
RPIX2D (&zpsf, i, j) = hold[j];
free (hold);
}
/* Insert array into twice as large array and compute FT.
No need to normalize !
*/
if ((status = AllocCmplxArray (ft, 2 * iso->nx, 2 * iso->ny)))
return (status);
/* Only works when both are even-sized. */
i1 = iso->nx / 2;
j1 = iso->ny / 2;
i2 = i1 + iso->nx;
j2 = j1 + iso->ny;
for (j = j1, kj = 0; j < j2; j++, kj++) {
for (i = i1, ki = 0; i < i2; i++, ki++)
RPIX2D (ft, i, j) = RPIX2D (&zpsf, ki, kj);
}
if ((status = fft2d (ft)))
return (status);
/* Now build "object" FT (central 11 X 11 portion).
No need to normalize !
*/
if ((status = AllocCmplxArray (fto, 2 * iso->nx, 2 * iso->ny)))
return (status);
wsize = 6;
i1 = iso->nx - wsize;
j1 = iso->ny - wsize;
i2 = iso->nx + wsize;
j2 = iso->ny + wsize;
for (j = j1, kj = iso->ny / 2 - wsize; j <= j2; j++, kj++) {
for (i = i1, ki = iso->nx / 2 - wsize; i <= i2; i++, ki++)
RPIX2D (fto, i, j) = RPIX2D (&zpsf, ki, kj);
}
if ((status = fft2d (fto)))
return (status);
FreeCmplxArray (&ziso);
FreeCmplxArray (&zpsf);
return (STIS_OK);
}