From a93b56495c9b3b6e9f00c05b4e7fd76bb31e4e07 Mon Sep 17 00:00:00 2001
From: Lorenzo Figini <lorenzo.figini@istp.cnr.it>
Date: Wed, 17 Apr 2013 15:59:34 +0000
Subject: [PATCH] added check in ic_gb for the case Nx0t=Ny0t=0

---
 src/gray.f | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/gray.f b/src/gray.f
index 20aa448..46505e2 100644
--- a/src/gray.f
+++ b/src/gray.f
@@ -3895,8 +3895,14 @@ c
 c
           pppx=x0t*rcixx+y0t*rcixy
           pppy=x0t*rcixy+y0t*rciyy
-          ppx=-pppx*gzt/(pppx*gxt+pppy*gyt)
-          ppy=-pppy*gzt/(pppx*gxt+pppy*gyt)
+          denpp=pppx*gxt+pppy*gyt
+          if (denpp.ne.0.0d0) then
+            ppx=-pppx*gzt/denpp
+            ppy=-pppy*gzt/denpp
+          else
+            ppx=0.0d0
+            ppy=0.0d0
+          end if
 c
           anzt=sqrt((1.0d0+gr2)/(1.0d0+ppx**2+ppy**2))
           anxt=ppx*anzt