[Clp] patch for Visual C++ floating-point model problem

[Arno Schödl]

With my floating-point model problem, I should have probably asked first which floating point model Clp/COIN assumes. This is the GCC compiler thread referring to the same problem:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

They apparently decided that GCC by default won't guarantee any rounding, similar to MSVC's /fp:fast. With the GCC -ffloat_store option, behavior is similar to MSVC /fp:precise, forcing rounding to 64 bit on assignments. I did not find this option in the COIN-Clp makefiles, and I do not recommend it because it hurts performance. If there is no other provision made that I overlooked, it seems to me that the current Clp code is incorrect, and something along the lines of my patch would be necessary.

Regards,

Arno

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