TestFPU Checks whether your computer suffers from the Floating Point Unit (FPU) accuracy degradation
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TestFPU Tags

Performance degradation floating point accuracy FPU speed Floating Point Unit Accuracy Degradation FPU Tester FPU Degradation Floating point emulation 10-bytes floating-point number floating-point arithmetic FPU comparison floating-point sample arbitrary floating point data calculate Floating point value Hex to Floating point

TestFPU Description

The TestFPU application was designed to be a small tool that checks whether your computer, running a 32-bit Windows, suffers from the Floating Point Unit (FPU) accuracy degradation. FPU is a separate part of your processor, performing fast and accurate calculations on floating-point (roughly speaking: non-integer) numbers. If you use any programs performing accurate calculations (mostly, but not only, scientific and engineering applications), you want your computer perform with the accuracy it was supposed to perform with. It turns out, under some Windows configurations the accuracy of your FPU is not up to specs. The nominal accuracy of the FPU is 19-20 decimal digits. If your system is affected, the delivered accuracy is about 16 digits, or roughly one thousand times worse than it should be. Sometimes you can live with that, sometimes not. For example, computing .33333333333333333333-1/3 should result in about 3E-20 if your FPU is OK. On affected systems the result will be about 2E-17. (Some applications, no names please, just cheat here, rounding either of these results to zero.) Even if you do not need this accuracy in the final results, some programs may depend on it in algorithms they use, and this may cause serious misbehaviors. As far as I was able to check, problem is not with the FPU itself (Intel, you're off the hook!) but with some memory-resident programs or device drivers, hooking themselves up to the operating system on a quite low level. They are supposed to do this without affecting anything except the things which they were written to do, but this is not the case.

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