CoCoA » CoCoA-5

If you run the two offending lines in a fresh CoCoA-5 then C5 reports an error that CurrentRing has no value! This cannot be correct behaviour since neither input nor output need any ring.

2013-01-24: JAA applied a quick fix to toric.cpkg5; the source code is rather ugly but we will not fix it because we expect it to be rewritten in C++ (sooner or later).

I further reduced the error:

/**/ M := matrix([[0, 1, 0], [0, 1, 0], [1, 0, 0]]);
/**/ MatSequentialToric(NewPolyRing(QQ,SymbolRange("x",1,NumRows(M))), M); 

2013-01-25 I misread the example; M is not an identity matrix.
Error due to the fact that MatSequentialToric is not checking input:
Toric does and correctly complains about the 0 column

Still some error (I guess of the same nature): this time triggered by

Use P ::= QQ[w,x,y,z,a,b,c];
I := Ideal(x*z-y^2, x*w-y*z);
M := matrix( /*QQ*/
        [[1, 1, -1, 0, 0, 0],
         [1, 0, 0, 1, 0, 0],
         [0, 1, 0, 0, 1, 0],
         [0, 0, 1, 0, 0, 1]]
        );
for i := 1 to 1000 Do
  Print i, "T";  A := Toric(I, [y]);
  Print "H ";  H := Toric(P, M);
EndFor;

Definitely valgrind time!

I suppose the bug never revealed itself before because malloc may well reserve slightly more space than you actually ask for (e.g. it may take a block whose length is a multiple of 16 bytes). Anyway valgrind should detect in a comprehensible way all cases where you read or write outside an allocated block.