tan, tanf, tanh - compute tangent

Syntax	#include <math.h> double tan(double x); C11 float tanf(float x); long double tanl(long double x); (End)
Description	These functions compute the trigonometric function tangent of a floating-point number x (within the permissible range of floating-point numbers). x is the floating-point number, specified in radians.
Return val.	tan(x)	Tangent of x if successful.
	+/-HUGE_VAL +/-HUGE_VALF +/-HUGE_VALL	depending on the function type and the sign of x, if an overflow occurs. errno is set to indicate the error.
Errors	tan() will fail if: ERANGE      The value of x causes an overflow.
See also	atan(), cos(), sin(), tanh(), math.h.