From 28fce7745bf588050dd2080260292ef0df628ad2 Mon Sep 17 00:00:00 2001
From: James Mitchell <jdm3@st-and.ac.uk>
Date: Thu, 14 Jun 2018 14:55:14 +0100
Subject: [PATCH] Fix bug in PartialPerm if length of img and dom differ

Resolve issue #2301.
---
 lib/pperm.gi              | 5 +++--
 tst/testinstall/pperm.tst | 6 ++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/pperm.gi b/lib/pperm.gi
index 6a652b55f53..40c2cea1ca6 100644
--- a/lib/pperm.gi
+++ b/lib/pperm.gi
@@ -545,12 +545,13 @@ function(arg)
     fi;
   elif Length(arg)=2 then  
     if IsSSortedList(arg[1]) and ForAll(arg[1], IsPosInt) and
-     IsDuplicateFreeList(arg[2]) and ForAll(arg[2], IsPosInt) then 
+     IsDuplicateFreeList(arg[2]) and ForAll(arg[2], IsPosInt) and
+     Length(arg[1]) = Length(arg[2]) then 
       return SparsePartialPermNC(arg[1], arg[2]); 
     else
       ErrorNoReturn("usage: the 1st argument must be a set of positive integers ",
       "and the 2nd argument must be a duplicate-free list of positive ",
-      "integers");
+      "integers of equal length to the first");
     fi;
   fi; 
  
diff --git a/tst/testinstall/pperm.tst b/tst/testinstall/pperm.tst
index 309ca6315a0..6d0a0990afb 100644
--- a/tst/testinstall/pperm.tst
+++ b/tst/testinstall/pperm.tst
@@ -2440,6 +2440,12 @@ gap> MultiplicativeZeroOp(x);
 gap> MultiplicativeZero(x);
 <empty partial perm>
 
+# Test PartialPerm (for sparse incorrect arg)
+gap> PartialPerm([1,2,8],[3,4,1,2]);
+Error, usage: the 1st argument must be a set of positive integers and the 2nd \
+argument must be a duplicate-free list of positive integers of equal length to\
+ the first
+
 #
 gap> SetUserPreference("PartialPermDisplayLimit", display);;
 gap> SetUserPreference("NotationForPartialPerm", notationpp);;