PHP Numbers Calculating Trigonometric Functions

PHP Numbers

Calculating Trigonometric Functions

Problem

You want to use trigonometric functions, such as sine, cosine, and tangent.

Solution

PHP supports many trigonometric functions natively: sin(), cos(), and tan():

            // cosine of 2 pi is 1, $result = 1
            $result = cos(2 * M_PI);

You can also use their inverses: asin(), acos(), and atan():

            // arctan of pi/4 is about 0.665773
            $result = atan(M_PI / 4);

Discussion

These functions assume all angles are in radians, not degrees. 

The function atan2() takes two variables $x and $y, and computes atan($x/$y). However, it always returns the correct sign because it uses both parameters when finding the quadrant of the result.

For secant, cosecant, and cotangent, you should manually calculate the reciprocal values of sin(), cos(), and tan():

            $n = 0.707;
            // secant of 0.707 is about 1.53951
            $secant = 1 / sin($n);

            // cosecant of 0.707 is about 1.31524
            $cosecant = 1 / cos($n);

            // cotangent of 0.707 is about 1.17051
            $cotangent = 1 / tan($n);

You can also use hyperbolic functions: sinh(), cosh(), and tanh(), plus, of course, asinh(), acosh(), and atanh(). The inverse functions, however, aren’t supported on Windows for PHP versions before 5.3.0.