1, trigonometric function double sin (double); Sinusoidal double cos (double); Cosine double tan (double); Tangent 2, inverse trigonometric function doubleasin (double); The result is between [-PI/2, PI/2]double acos (double); The result is between [0, PI]double atan (double); Arctangent (principal value), the result is between [-pi/2, pi/2] double atan2 (double, double); Arctangent (integer value), the result is between [-PI, PI]3, hyperbolic trigonometric function double sinh (double); Double cosh (double); Double tanh (double); 4. Exponential and Logarithmic Double Frexp (Double Value, int * exp); This is a method to split a value into a fractional part f and an exponential part exp (base 2), and return the fractional part f, that is, f * 2 exp. Where the value of f is in the range of 0.5~ 1.0 or 0. double ldexp(double x，int exp)； This function is just the opposite of the function of the frexp function above, and its return value is x * 2 exp double MODF (double value, double * iptr); Split a value and return its fractional part, with iptr pointing to the integer part. Double; Logarithmic doublelog10 (double) based on e; Logarithmic double pow(double x, doubley) with 10 as the radix; Calculate Y-power floating-point powf (floating-point X, floating-point Y) based on X; Functions are the same as pow, except that the input and output are floating-point numbers Double EXP (double); Find the power of natural number e, double sqrt (double); Square root 5, circular double)； ceiling; Round up and return the smallest integer double floor (double) not less than x; Take down the integer and return the largest integer not greater than x, that is, Gaussian function [x]6 and absolute value intabs (int i); Find the absolute value of the integer double fabs (double); Actual absolute value double cab (struct complex znum); Find the absolute value of complex number 7. Standardized floating-point number double frexp (double f, int * p); Standardized floating-point number, f = x * 2^p, it is known that f finds x, p (x is between [0.5, 1]) double ldexp (double x, int p); Contrary to frexp, it is known that x and p can find f8, integer and remainder double modf (double, double *); Pass the pointer back to the integer part of the parameter and return the decimal part of double fmod (double, double); Returns the remainder of the division of two parameters: 9. Other double sea waves (double x, double y); Given the length of two right-angled sides of a right-angled triangle, find the hypotenuse length, double ldexp (double x, int exposure); Calculate x * (exponential power of 2) doublepoly (doublex, int degree, doublecoeffs []); Calculate polynomial int matherr (structexception * e); Mathematical error calculation processor