Standard C Library Functions in math.h

double acos(double x); Trigonometric function returns the angle whos cosine is x. The value of x must be between -1 and +1, otherwise a domain error occurs. The angle is measured in radians.
double asin(double x); Returns the angle whos sine is x. The angle returned is in radians. A value of x must be between -1 and +1.
double atan(double x); Returns angle whos tangent is x. The angle is always between -PI/2 and +PI/2 radians.
double atan2(double y, double x); Returns the angle based on y being the opposite side and x being the adjacent side of a right triangle. Note: Whether y and/or x are negative or positive determines which quadrant the angle is in.
double ceil(double x); Returns the smallest integral value that is greater than or equal to x.
double cos(double x); Returns the cosine of the angle x, x must be in radians.
double cosh(double x); Returns the hyperbolic cosine of the angle x.
double exp(double x); Returns the exponential function of x. In mathematics it is written as ex.
double fabs(double x); Returns the absolute value of x.
double floor(double x); Returns the largest integral value that is less than or equal to x.
double fmod(double x, double y); Returns the floating point remainder of x/y.
double frexp(double x, int *exp); Returns a normalized fraction and an integral power of 2. The power of 2 is returned in exp.
double ldexp(double x, int exp); Returns x*2exp.
double log(double x); Returns the natural logarithm of x (logarithm to base e).
double log10(double x); Returns the logarithm of x (logarithm to the base 10).
double modf(double x, double *i); Divides x into integral and fractional parts. The integral part is returned in i. The return value of the function is the fractional part.
double pow(double x, double y); Returns the value of xy.
double sin(double x); Returns the sine of the angle x. The angle x must be in radians.
double sinh(double x); Returns the hyperbolic sine of the angle x.
double sqrt(double x); Returns the square root of x. x must be positive.
double tan(double x); Returns the tangent of the angle x. x must be in radians.
double tanh(double x); Returns the hyperbolic tangent of x.