[Gcl-devel] RE: [Maxima] modulus

[Stavros Macrakis]

> > in the GCL version, there is a bug where huge 
> > integer calculations corrupt memory.

> Am unaware of this.  Please file as detailed a report as 
> possible if you believe this to be a GCL bug.

In a fresh GCL 2.5.0, (expt 234 234234) immediately crashes with an
illegal instruction (0xc000001d) at location 0x0053f611.

In a fresh Maxima 5.9.0 built on GCL 2.5.0, 234^234234 will return
(though I have not checked whether the result is correct), but if you
repeat the command a couple of times, you get an error:

(C1) 234^234234$
(C2) 234^234234$
(C3) 234^234234$
Error: Caught fatal error [memory may be damaged]
Error signalled by EXPTRL.

After this, other things go wrong,

rat((x+1)^20);
Error: Caught fatal error [memory may be damaged]
Error signalled by PEXPT.

Sometimes I think it crashes the process completely, but I haven't been
able to reproduce that right now.

Though 234^234234 is large, it is not *that* large -- about 60,000
32-bit words.  And if the problem is some sort of memory allocation
overflow, it should give a relevant error, not just randomly fail.

Perhaps this has been fixed in a more recent GCL...?

       -s