# Floating Point Precision (fp:precise vs. fp:fast)

In C or C++, does the compiler option of floating point precision really make a difference in real world (small/indie) games?

From my observations, setting fp:fast is many times faster than fp:precise and from what I understand here ( https://stackoverflow.com/questions/6889522/fpfast-vs-fpprecise-what-kind-of-errors-can-i-encounter ) the precision difference between the two compiler options only changes from the 16th digit of a floating point number.

Has anyone encountered an example when using fp:fast went terribly wrong for 2D or 3D games?

Edit: To clarify, I am not asking about the precision of floating point values themselves (ie. float vs double vs decimal). Only about precision related to the compiler option.

• @MaikSemder Basically just use fp:fast then, unless you really want the fp:precise if you notice various strange issues (could be noticed in complex computations in games, such as physics as @postgoodism said). Thanks, was wondering on this. Oct 8 '18 at 18:28