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-rw-r--r--src/diffraction-gpu.c1
-rw-r--r--src/diffraction.c82
2 files changed, 57 insertions, 26 deletions
diff --git a/src/diffraction-gpu.c b/src/diffraction-gpu.c
index 9b96f112..e7449148 100644
--- a/src/diffraction-gpu.c
+++ b/src/diffraction-gpu.c
@@ -36,7 +36,6 @@
#define SAMPLING (4)
#define BWSAMPLING (10)
-
#define SINC_LUT_ELEMENTS (4096)
diff --git a/src/diffraction.c b/src/diffraction.c
index a7cf90c7..13a3dd95 100644
--- a/src/diffraction.c
+++ b/src/diffraction.c
@@ -29,12 +29,53 @@
#define SAMPLING (4)
#define BWSAMPLING (10)
+#define SINC_LUT_ELEMENTS (4096)
+
+
+static double *get_sinc_lut(int n)
+{
+ int i;
+ double *lut;
+
+ lut = malloc(SINC_LUT_ELEMENTS*sizeof(double));
+ lut[0] = n;
+ if ( n == 1 ) {
+ for ( i=1; i<SINC_LUT_ELEMENTS; i++ ) {
+ lut[i] = 1.0;
+ }
+ } else {
+ for ( i=1; i<SINC_LUT_ELEMENTS; i++ ) {
+ double x, val;
+ x = (double)i/SINC_LUT_ELEMENTS;
+ val = fabs(sin(M_PI*n*x)/sin(M_PI*x));
+ lut[i] = val;
+ }
+ }
+
+ return lut;
+}
+
+
+static double interpolate_lut(double *lut, double val)
+{
+ double i, pos, f;
+ unsigned int low, high;
+
+ pos = SINC_LUT_ELEMENTS * modf(val, &i);
+ low = (int)pos; /* Discard fractional part */
+ high = low + 1;
+ f = modf(pos, &i); /* Fraction */
+ if ( high == SINC_LUT_ELEMENTS ) high = 0;
+
+ return (1.0-f)*low + f*high;
+}
static double lattice_factor(struct rvec q, double ax, double ay, double az,
double bx, double by, double bz,
double cx, double cy, double cz,
- int na, int nb, int nc)
+ double *lut_a, double *lut_b,
+ double *lut_c)
{
struct rvec Udotq;
double f1, f2, f3;
@@ -43,30 +84,10 @@ static double lattice_factor(struct rvec q, double ax, double ay, double az,
Udotq.v = bx*q.u + by*q.v + bz*q.w;
Udotq.w = cx*q.u + cy*q.v + cz*q.w;
- /* At exact Bragg condition, f1 = na */
- if ( na > 1 ) {
- f1 = sin(M_PI*(double)na*Udotq.u) / sin(M_PI*Udotq.u);
- } else {
- f1 = 1.0;
- }
+ f1 = interpolate_lut(lut_a, Udotq.u);
+ f2 = interpolate_lut(lut_b, Udotq.u);
+ f3 = interpolate_lut(lut_c, Udotq.u);
- /* At exact Bragg condition, f2 = nb */
- if ( nb > 1 ) {
- f2 = sin(M_PI*(double)nb*Udotq.v) / sin(M_PI*Udotq.v);
- } else {
- f2 = 1.0;
- }
-
- /* At exact Bragg condition, f3 = nc */
- if ( nc > 1 ) {
- f3 = sin(M_PI*(double)nc*Udotq.w) / sin(M_PI*Udotq.w);
- } else {
- f3 = 1.0;
- }
-
- /* At exact Bragg condition, this will multiply the molecular
- * part of the structure factor by the number of unit cells,
- * as desired (more scattering from bigger crystal!) */
return f1 * f2 * f3;
}
@@ -331,6 +352,9 @@ void get_diffraction(struct image *image, int na, int nb, int nc,
double bx, by, bz;
double cx, cy, cz;
float klow, khigh, bwstep;
+ double *lut_a;
+ double *lut_b;
+ double *lut_c;
cell_get_cartesian(cell, &ax, &ay, &az, &bx, &by, &bz, &cx, &cy, &cz);
@@ -344,6 +368,10 @@ void get_diffraction(struct image *image, int na, int nb, int nc,
khigh = 1.0/(image->lambda*(1.0 - image->beam->bandwidth/2.0));
bwstep = (khigh-klow) / BWSAMPLING;
+ lut_a = get_sinc_lut(na);
+ lut_b = get_sinc_lut(nb);
+ lut_c = get_sinc_lut(nc);
+
for ( fs=0; fs<image->width; fs++ ) {
for ( ss=0; ss<image->height; ss++ ) {
@@ -371,7 +399,7 @@ void get_diffraction(struct image *image, int na, int nb, int nc,
f_lattice = lattice_factor(q, ax, ay, az,
bx, by, bz,
cx, cy, cz,
- na, nb, nc);
+ lut_a, lut_b, lut_c);
I_molecule = molecule_factor(intensities,
phases, flags, q,
@@ -397,4 +425,8 @@ void get_diffraction(struct image *image, int na, int nb, int nc,
}
progress_bar(fs, image->width-1, "Calculating diffraction");
}
+
+ free(lut_a);
+ free(lut_b);
+ free(lut_c);
}