std::pow produce different result in 32 bit and 64 bit application

Question

I have found the mismatch in the result of some complex calculations. When i thoroughly observed the intermediate results, its the std::pow function which creates that misma

Answer 1

From the wikipedia page on long double

On the x86 architecture, most C compilers implement long double as the 80-bit extended precision type supported by x86 hardware [...]. An exception is Microsoft Visual C++ for x86, which makes long double a synonym for double.

So when you are compiling on 32 bit long double = double, but on x64 long double is actually an 80 bit floating point, so the results are different.