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-rw-r--r--src/diffraction.c65
1 files changed, 62 insertions, 3 deletions
diff --git a/src/diffraction.c b/src/diffraction.c
index 92e18521..82e5c132 100644
--- a/src/diffraction.c
+++ b/src/diffraction.c
@@ -434,7 +434,7 @@ static int compare_samples(const void *a, const void *b)
static struct sample *get_gaussian_spectrum(double eV_cen, double eV_step,
- double sigma, int spec_size)
+ double sigma, int spec_size, double eV_start)
{
struct sample *spectrum;
int i;
@@ -443,7 +443,12 @@ static struct sample *get_gaussian_spectrum(double eV_cen, double eV_step,
spectrum = malloc(spec_size * sizeof(struct sample));
if ( spectrum == NULL ) return NULL;
- eV = eV_cen - (spec_size/2)*eV_step;
+ if (eV_start == 0) { /* eV starts at 3 sigma below the mean*/
+ eV = eV_cen - (spec_size/2)*eV_step;
+ } else {
+ eV = eV_start;
+ }
+
for ( i=0; i<spec_size; i++ ) {
spectrum[i].k = 1.0/ph_eV_to_lambda(eV);
@@ -568,7 +573,7 @@ struct sample *generate_SASE(struct image *image, gsl_rng *rng)
* points */
double eV_step = 6.0*sigma/(spec_size-1);
- spectrum = get_gaussian_spectrum(eV_cen, eV_step, sigma, spec_size);
+ spectrum = get_gaussian_spectrum(eV_cen, eV_step, sigma, spec_size,0);
/* Add SASE-type noise to Gaussian spectrum */
add_sase_noise(spectrum, spec_size, rng);
@@ -591,6 +596,60 @@ struct sample *generate_SASE(struct image *image, gsl_rng *rng)
return spectrum;
}
+struct sample *generate_twocolour(struct image *image)
+{
+ struct sample *spectrum;
+ struct sample *spectrum1;
+ struct sample *spectrum2;
+ int i;
+
+ double halfwidth = image->bw/2; /* eV */
+
+ const int spec_size = 1024;
+ double eV_cen1; /* Central photon energy for first colour */
+ double eV_cen2; /* Central photon energy for second colour */
+ eV_cen1 = ph_lambda_to_eV(image->lambda) - halfwidth;
+ eV_cen2 = ph_lambda_to_eV(image->lambda) + halfwidth;
+
+ /* Hard-code sigma to be 1/5 of bandwidth */
+ double sigma = image->bw/5; /* eV */
+
+ /* The spectrum will be calculated to a resolution which spreads six
+ * sigmas of the original (no SASE noise) Gaussian pulse over spec_size
+ * points */
+ double eV_start = eV_cen1 - 3*sigma;
+ double eV_end = eV_cen2 + 3*sigma;
+ double eV_step = (eV_end - eV_start)/(spec_size-1);
+
+ spectrum1 = get_gaussian_spectrum(eV_cen1, eV_step, sigma, spec_size, eV_start);
+ spectrum2 = get_gaussian_spectrum(eV_cen2, eV_step, sigma, spec_size, eV_start);
+
+ spectrum = malloc(spec_size * sizeof(struct sample));
+ if ( spectrum == NULL ) return NULL;
+
+ for ( i=0; i<spec_size; i++ ) {
+ spectrum[i].weight = spectrum1[i].weight + spectrum2[i].weight;
+ spectrum[i].k = spectrum1[i].k;
+ }
+
+ /* Normalise intensity (before taking restricted number of samples) */
+ double total_weight = 0.0;
+ for ( i=0; i<spec_size; i++ ) {
+ total_weight += spectrum[i].weight;
+ }
+
+ for ( i=0; i<spec_size; i++ ) {
+ spectrum[i].weight /= total_weight;
+ }
+
+ /* Sort samples in spectrum by weight. Diffraction calculation will
+ * take the requested number, starting from the brightest */
+ qsort(spectrum, spec_size, sizeof(struct sample), compare_samples);
+
+ image->spectrum_size = spec_size;
+
+ return spectrum;
+}
void get_diffraction(struct image *image, int na, int nb, int nc,
const double *intensities, const double *phases,