Is float slower than double? Does 64 bit program run faster than 32 bit program?

Is using float type slower than using double type?

I heard that modern Intel and AMD CPUs can do calculations with doubles faster than with floats.

What about standard math functions (sqrt, pow, log, sin, cos, etc.)? Computing them in single-precision should be considerably faster because it should require less floating-point operations. For example, single precision sqrt can use simpler math formula than double precision sqrt. Also, I heard that standard math functions are faster in 64 bit mode (when compiled and run on 64 bit OS). What is the definitive answer on this?

c# java c++ c static-typing

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Your first question has already been answer here on SO.

Your second question is entirely dependent on the "size" of the data you are working with. It all boils down to the low level architecture of the system and how it handles large values. 64-bits of data in a 32 bit system would require 2 cycles to access 2 registers. The same data on a 64 bit system should only take 1 cycle to access 1 register.

Everything always depends on what you're doing. I find there are no fast and hard rules so you need to analyze the current task and choose what works best for your needs for that specific task.

answered 2011-04-21T01:19:17.380

Is float slower than double? Does 64 bit program run faster than 32 bit program?

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