From 845c338b3032837ce37e02fbed0a82879030537d Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Fri, 8 Jan 2021 10:49:17 +0100
Subject: locate_peak_on_panel: Check sign of 1/mu

---
 libcrystfel/src/geometry.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'libcrystfel/src/geometry.c')

diff --git a/libcrystfel/src/geometry.c b/libcrystfel/src/geometry.c
index 510fa833..e61f6fc8 100644
--- a/libcrystfel/src/geometry.c
+++ b/libcrystfel/src/geometry.c
@@ -103,6 +103,10 @@ static int locate_peak_on_panel(double x, double y, double z, double k,
 
 	*pfs = fs;  *pss = ss;
 
+	/* If "mu" is negative, then the reflection is in the
+	 * wrong direction */
+	if ( one_over_mu < 0.0 ) return 0;
+
 	/* Now, is this on this panel? */
 	if ( fs < 0.0 ) return 0;
 	if ( fs >= p->w ) return 0;
-- 
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