RingMapOntoRewrittenResidueClassRing avoids creating a new ring if no…

…t necessary
homalg-project · May 10, 2019 · 0c7bcbc · 0c7bcbc
1 parent 0818f01
commit 0c7bcbc
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/MatricesForHomalg/PackageInfo.g b/MatricesForHomalg/PackageInfo.g
@@ -5,7 +5,7 @@ PackageName := "MatricesForHomalg",
 Subtitle := "Matrices for the homalg project",
 
 Version := Maximum( [
-  "2019.02.10", ## Mohamed's version
+  "2019.02.13", ## Mohamed's version
 ## this line prevents merge conflicts
   "2019.02.11", ## Fabian's version
 ## this line prevents merge conflicts

diff --git a/MatricesForHomalg/gap/Tools.gi b/MatricesForHomalg/gap/Tools.gi
@@ -7269,9 +7269,13 @@ InstallMethod( RingMapOntoRewrittenResidueClassRing,
 
     zero_rows := ZeroRows( matrix - images );
 
-    indets := indets{zero_rows};
-
-    S := k * List( indets, String );
+    if Length( indets ) = Length( zero_rows ) and
+       IsIdenticalObj( k, CoefficientsRing( A ) ) then
+        S := A;
+    else
+        indets := indets{zero_rows};
+        S := k * List( indets, String );
+    fi;
 
     if not zero_rows = [ ] then
         map := RingMap( indets, S, R );