From dc76f055cefcfc70f97f4c5520e65eec7e662fcf Mon Sep 17 00:00:00 2001
From: Thomas White <taw27@cam.ac.uk>
Date: Thu, 19 Mar 2009 12:07:53 +0000
Subject: Send a random selection of reflections to DirAx if more than 1,000
 are present

---
 src/dirax.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 62 insertions(+), 5 deletions(-)

diff --git a/src/dirax.c b/src/dirax.c
index 2924380..7c79412 100644
--- a/src/dirax.c
+++ b/src/dirax.c
@@ -365,12 +365,59 @@ void dirax_rerun(ControlContext *ctx)
 	ctx->dirax_step = 7;
 }
 
+
+static void dirax_send_random_selection(ReflectionList *r, int n, FILE *fh)
+{
+	char *used;
+	int i;
+
+	used = malloc(n*sizeof(char));
+
+	for ( i=0; i<n; i++ ) {
+		used[i] = '-';
+	}
+
+	for ( i=0; i<1000; i++ ) {
+
+		Reflection *ref;
+		int done;
+		int j;
+		long long int ra;
+
+		done = 0;
+		while ( !done ) {
+			ra = ((long long int)random() * (long long int)n);
+			ra /= RAND_MAX;
+			if ( used[ra] == 'U' ) {
+				printf("%lli - already used\n", ra);
+			} else {
+				done = 1;
+			}
+		}
+		printf("Selected reflection %lli\n", ra);
+
+		/* Dig out the correct reflection. A little faffy
+		 * because of the linked list */
+		ref = r->reflections;
+		for ( j=0; j<ra; j++ ) {
+			ref = ref->next;
+		}
+		fprintf(fh, "%10f %10f %10f %8f\n",
+					ref->x/1e10, ref->y/1e10,
+					ref->z/1e10, ref->intensity);
+		used[ra] = 'U';
+
+	}
+}
+
+
 void dirax_invoke(ControlContext *ctx)
 {
 	FILE *fh;
 	Reflection *ref;
 	unsigned int opts;
 	int saved_stderr;
+	int n;
 
 	if ( ctx->dirax ) {
 		dirax_rerun(ctx);
@@ -386,11 +433,21 @@ void dirax_invoke(ControlContext *ctx)
 	}
 	fprintf(fh, "%f\n", 0.5);  /* Lie about the wavelength.  DirAx can't
 				    *  handle the truth. */
-	ref = ctx->reflectionlist->reflections;
-	while ( ref ) {
-		fprintf(fh, "%10f %10f %10f %8f\n", ref->x/1e10, ref->y/1e10,
-						ref->z/1e10, ref->intensity);
-		ref = ref->next;
+
+	n = ctx->reflectionlist->n_reflections;
+	printf("DX: There are %i reflections - ", n);
+	if ( n > 1000 ) {
+		printf("sending a random selection to DirAx\n");
+		dirax_send_random_selection(ctx->reflectionlist, n, fh);
+	} else {
+		printf("sending them all to DirAx\n");
+		ref = ctx->reflectionlist->reflections;
+		while ( ref ) {
+			fprintf(fh, "%10f %10f %10f %8f\n",
+					ref->x/1e10, ref->y/1e10,
+					ref->z/1e10, ref->intensity);
+			ref = ref->next;
+		}
 	}
 	fclose(fh);
 
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