From 3611be8ba011392cf35f0bb29a49030e7b7adb59 Mon Sep 17 00:00:00 2001
From: Steve Franke <s.j.franke@icloud.com>
Date: Fri, 3 May 2019 10:51:45 -0500
Subject: [PATCH] Try to avoid an array bounds error that has been reported by
 a user. Cause unknown.

---
 lib/ft8/sync8.f90 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/ft8/sync8.f90 b/lib/ft8/sync8.f90
index 3924f1bad..219c6ebf1 100644
--- a/lib/ft8/sync8.f90
+++ b/lib/ft8/sync8.f90
@@ -89,7 +89,12 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,   &
   enddo
   iz=ib-ia+1
   call indexx(red(ia:ib),iz,indx)
-  ibase=indx(nint(0.40*iz)) - 1 + ia
+  npctile=nint(0.40*iz)
+  if(npctile.lt.1) then ! something is wrong; bail out
+    ncand=0
+    return;
+  endif
+  ibase=indx(npctile) - 1 + ia
   if(ibase.lt.1) ibase=1
   if(ibase.gt.nh1) ibase=nh1
   base=red(ibase)