G++ 4.3.4 vs.G++ 4.5.2???

[Jonathan Wakely]

On 13 June 2011 11:24, Jan Chludzinski wrote:
> Just finished compiling some numerical code (developed using the
> Borland C++ compiler) using G++ 4.3.4 (that came with Cygwin 1.7). The
> answers are different from what I get using the Borland compiler
> (circa 2002).  I have known correct answers from some NASA code and
> compare against those.
>
> I've transitioned of late to Code::Blocks using the latest MinGW.
> MinGW comes with G++ 4.5.2.  I compiled using this compiler and it
> once again works (I get the same answers as the NASA code).
>
> Are there known problems with G++ 4.3.4?
>
> BTW, the original code was infinite looping until I replaced the old style:
>
> for (i=0; i<WHATEVER; i++) ..
>
> with i declared within the routine (i.e., function) with:
>
> for (int i=0; i<WHATEVER; i++) ...

Are you using x86? Are you telling the compiler to use SSE registers
for floating point instead of the 387 registers?

Does using "-march=pentium3 -mfpmath=sse" with GCC 4.3.4 give the
expected results?