Floating point division vs floating point multiplication

Question

Is there any (non-microoptimization) performance gain by coding

float f1 = 200f / 2

in comparision to

float f2 = 200f * 0.5         


        

Answer 1

Yes. Every FPU I am aware of performs multiplications much faster than divisions.

However, modern PCs are very fast. They also contain pipelining archtectures that can make the difference negligable under many circumstances. To top it off, any decent compiler will perform the division operation you showed at compile time with optimizations turned on. For your updated example, any decent compiler would perform that transformation itself.

So generally you should worry about making your code readable, and let the compiler worry about making it fast. Only if you have a measured speed issue with that line should you worry about perverting your code for the sake of speed. Compilers are well aware of what is faster than what on their CPU's, and are generally much better optimizers than you can ever hope to be.