Sorry if this is a duplicate message. I am not sure if my previous attempt to
send this message got there or not.
Several months ago I downloaded fermat.exe from the Mersenne.org site
("zip file" at http://www.mersenne.org/fermat.htm). This program attempts
to find factors of Fermat numbers (F16 to F20) using ECM factoring.
I have run it occasionally, and it seems to work. (I have found some of
the known factors, but no new ones yet.)
More recently, I downloaded the source code from Perfectly Scientific
Inc (link is on the same page as above). I have compiled the source code
successfully, but the resulting program does not seem to be working, since I have
found none of the known factors with several runs of the program. (The output to
the screen looks the same as George's executable, except for not finding any
factors.) I even modified the line that says "seed = random number"
to say "seed = value", where "value" is a number that resulted in finding a factor
in the original executable. (Note: the original executable and my executable
are for Windows 95/NT.)
My first few compiles were with Watcom C. I then tried MS Visual C/C++,
using the command line that was suggested in the comments in the file fermat.c:
cl -O2 fermat.c fgiants.c giants.c
A couple of "test programs" are included with the Perf-Sci source files.
These programs use giants.c (but not fgiants.c). I tried these two (with
Watcom C) and they seem to work OK.
The comments at the top of each of the files used for "fermat.exe"
indicate that changes have been made since George's executable was created.
Perhaps Perf-Sci introduced a bug somewhere? Does anyone have any other ideas
about what the problem could be?
