Fix IsCheapConwayPolynomial( p, 1 ) for p < 1000 (#5531)

gap-system · Nov 17, 2023 · 962db5c · 962db5c
1 parent 6f50fa7
commit 962db5c
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/lib/polyconw.gi b/lib/polyconw.gi
@@ -502,15 +502,15 @@ InstallGlobalFunction( IsCheapConwayPolynomial, function( p, n )
   fi;
   # this is not very precise, hopefully good enough for the moment
   if p < 41 then
-    if n < 100 and IsPrimeInt(n) then
+    if n < 100 and (n = 1 or IsPrimeInt(n)) then
       return true;
     fi;
   elif p < 100 then
-    if n < 40 and IsPrimeInt(n) then
+    if n < 40 and (n = 1 or IsPrimeInt(n)) then
       return true;
     fi;
   elif p < 1000 then
-    if n < 14 and IsPrimeInt(n) then
+    if n < 14 and (n = 1 or IsPrimeInt(n)) then
       return true;
     fi;
   elif p < 2^48 then

diff --git a/tst/testinstall/ffeconway.tst b/tst/testinstall/ffeconway.tst
@@ -52,6 +52,8 @@ gap> fieldpairs := Concatenation(List(fieldsizes, pd -> List(Filtered([1..pd[2]-
   [ 257, 11, 1 ], [ 65521, 2, 1 ], [ 65537, 2, 1 ], [ 268435399, 2, 1 ], 
   [ 4294967291, 2, 1 ], [ 1152921504606846883, 3, 1 ], 
   [ 18446744073709551629, 2, 1 ] ]
+gap> IsCheapConwayPolynomial( 997, 1 );
+true
 
 #
 # construct generating elements