{{keywords>wiki library source code example reference}}
====== atan2 ======

<code cpp>
    double atan2(double , double );
</code>
calculates arctangent from 2 numbers

===== cpp Sourcecode Example =====

<code cpp>
#include <iostream> /* including standard library */
#include <cmath> /* including math library */

using namespace std;
int main ( void ){
    double a=1.2, b=-2.6, res;
    res = atan2(a, b) * 90 / 3.17;
    
    //cout.setf(ios::fixed, ios::floatfield);
    cout.precision(7);

    cout << "atan2 from " << a << " and " << b << " is "  << res << endl;
    return 0;
}
</code>
===== output =====
    atan2 from 1.2 and -2.6 is 76.91692