在Linux，Mac OS X和Windows之间不同的数学舍入行为 [英] Different math rounding behaviour between Linux, Mac OS X and Windows

问题描述

您好，

我开发了一些混合的C / C ++ code，一些密集的数值计算。当Linux和Mac OS X编译我得到的结果非常相似模拟结束后。在Windows中，程序编译，以及，但我得到非常不同的结果，有时程序似乎并没有工作。

I developed some mixed C/C++ code, with some intensive numerical calculations. When compiled in Linux and Mac OS X I get very similar results after the simulation ends. In Windows the program compiles as well but I get very different results and sometimes the program does not seem to work.

我用GNU编译器中的所有系统。有些朋友建议我加-frounding，数学和现在的windows版本似乎工作较稳定，但Linux和OS X中，他们的结果，根本不改变。

I used GNU compilers in all systems. Some friend recommend me to add -frounding-math and now the windows version seems to work more stable, but Linux and Os X, their results, do not change at all.

你能推荐其他选项来赢和Linux / OSX版本之间有更多的一致性？

Could you recommend another options to get more concordance between Win and Linux/OSX versions?

感谢

Pd积。我也试过-O0（不优化）和指定-m32

P.D. I also tried -O0 (no optimizations) and specified -m32

推荐答案

我无法在Windows中执行说话，但英特尔芯片包含80位的浮点寄存器，可以比规定给予更大precision在IEEE-754浮点标准。您可以尝试调用这个例程的的main（）的应用程序（基于英特尔芯片平台）的：

I can't speak to the implementation in Windows, but Intel chips contain 80-bit floating point registers, and can give greater precision than that specified in the IEEE-754 floating point standard. You can try calling this routine in the main() of your application (on Intel chip platforms):

inline void fpu_round_to_IEEE_double()
{
   unsigned short cw = 0;
   _FPU_GETCW(cw);        // Get the FPU control word
   cw &= ~_FPU_EXTENDED;  // mask out '80-bit' register precision
   cw |= _FPU_DOUBLE;     // Mask in '64-bit' register precision
   _FPU_SETCW(cw);        // Set the FPU control word
}

我的认为的，这是由@Alok讨论的舍入模式是不同的。

I think this is distinct from the rounding modes discussed by @Alok.

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