Math Constants in C++

August 17, 2012 in c++, Tutorial | No comments

Some of my colleagues didn't know that you can use mathematical constants that are part of "cmath". Here is the small snippet that shows how to use PI from cmath library. Be aware that you need to write "#define _USE_MATH_DEFINES" before you include cmath.

 

View Code CPP
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#define _USE_MATH_DEFINES
 
#include 
#include 
 
using namespace std;
 
int main() {
 
  cout << M_PI << endl;
 
  return 0;
}

 

The full list of constants is:

 

Symbol Expression Value
M_E e 2.71828182845904523536
M_LOG2E log2(e) 1.44269504088896340736
M_LOG10E log10(e) 0.434294481903251827651
M_LN2 ln(2) 0.693147180559945309417
M_LN10 ln(10) 2.30258509299404568402
M_PI pi 3.14159265358979323846
M_PI_2 pi/2 1.57079632679489661923
M_PI_4 pi/4 0.785398163397448309616
M_1_PI 1/pi 0.318309886183790671538
M_2_PI 2/pi 0.636619772367581343076
M_2_SQRTPI 2/sqrt(pi) 1.12837916709551257390
M_SQRT2 sqrt(2) 1.41421356237309504880
M_SQRT1_2 1/sqrt(2) 0.707106781186547524401

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