fix a bug in the position generation in gen-dark-matter

This commit fixes a bug in gen-dark matter which was causing the positions to
all be generated with positive x, y, and z values. Doh!

1 files changed, 3 insertions, 3 deletions

diff --git a/utils/gen-dark-matter b/utils/gen-dark-matter
index 007dde3..06b146f 100755
--- a/utils/gen-dark-matter
+++ b/utils/gen-dark-matter
@@ -145,12 +145,12 @@ MCPL_HEADER="""
 class MyTemplate(string.Template):
     delimiter = '@'
 
-def rand_sphere2(R):
+def rand_ball(R):
     """
     Generates a random point inside a sphere of radius R.
     """
     while True:
-        pos = np.random.rand(3)*R
+        pos = (np.random.rand(3)*2-1)*R
 
         if np.linalg.norm(pos) < R:
             break
@@ -323,7 +323,7 @@ if __name__ == '__main__':
         f.write("%i %i\n" % (args.n, 10))
 
         for v1, v2 in islice(gen_decay(args.M,args.E,m1,m2),args.n):
-            pos = rand_sphere2(PSUP_RADIUS)
+            pos = rand_ball(PSUP_RADIUS)
             p1 = np.linalg.norm(v1[1:])
             p2 = np.linalg.norm(v2[1:])
             f.write("    %i %i %f %f %f %f %f %f %f %f\n" % (2,args.p1,pos[0], pos[1], pos[2],0.0, v1[0], v1[1]/p1, v1[2]/p1, v1[3]/p1))