c++ program produces bad results

[Gene Smith]

I have a one-file c++ program that builds and runs fine with g++ on 
linux (f12). It also builds fine when built with i686-pc-mingw32-g++ on 
f12. However, when run under window or wine on linux it produces zeros 
for all double outputs and other incorrect integer results. There are no 
errors indicated other than the output is obviously wrong. Is there a 
trick to getting math intensive c++ programs to work when running 
mingw32 programs?

-gene