Whats the difference and what should I use

[ravel1989]

Hello, whats the difference between float(atan(14.865f)) and atanf(14.865f)
and what should I use?

[Cubbi]

In C++ (if you #include <cmath> and use std::atan (or using namespace std), They are exact same thing. You should skip the redundant cast and use std::atan(14.865f)

If you're using the C math library (from #include <math.h> ), atan returns a double, which is then cast to float, and the result may, in principle, depend on the currently installed floating-point rounding mode.

example:

1 2 3 4 5 6 7 8 9 10 11 12

#include <math.h> #include <fenv.h> #include <iostream> #include <iomanip> int main() { fesetround(FE_UPWARD); std::cout << std::setprecision(100) << float(atan(14.865f)) << '\n' << atanf(14.865f) << '\n'; }

1.503625392913818359375 1.50362551212310791015625

online demo: http://coliru.stacked-crooked.com/a/3c7d79c2dc840063

[ravel1989]

Thank you!