1, Description: C library function? Double fabs(double x), returns floating-point number x? Absolute value of.
2. declaration: declaration of fabs () function: double fabs (double x).
3. Function: This function returns the absolute value of floating-point number X.
4. Description: Calculates |x| and returns x when x is not negative, otherwise returns-x.
5. Example: Demonstrate the use of fabs () function.
6. Compile: Let's compile and run the above program, which will produce the following results:
Extended data:
Math.h, a mathematical function library, can generally be found in C programming, # include.
Math.h header file declares some commonly used mathematical operations, such as power, root and so on. There are many of these header files, which are stored in the installation directory of VC software. For example:
1, trigonometric function
Double)； crime; sine
Double cos (double); cosine
Shuangtan (double); tangent
2. Inverse trigonometric function
double asin(double)； The result is between [-PI/2, PI/2]
Double acos (double); The result is between [0, PI]
Double (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 functions
Double sinh (double);
Double cosh (double);
Double tanh (double);
4. Exponents and Logarithms
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 frexp function above, and the 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; Logarithm based on e
double log 10(double)； Logarithm based on 10
Double power (double x, double y); Calculate the y power of x
Floating point powf (floating point x, floating point y); This function is the same as pow, except that the input and output are single-precision floating-point numbers.
Double exp (double); Find the power of natural number e
double sqrt(double)； square root
5, rounding
Double ceiling (double); Rounds up and returns the smallest integer not less than x.
Double floor (double); Take the integer down and return the largest integer not greater than x, which is the Gaussian function [x]
6. Absolute value
int ABS(int I)； Find the absolute value of an integer
Double wafer factory (double); Absolute value of realistic type
Double cab (complex structure Znum); Find the absolute value of a complex number
7. Standardized floating-point numbers
double frexp (double f，int * p)； Standardized floating-point number, f = x * 2^p, f is known to find x, p (x is between [0.5, 1]).
double ldexp (double x，int p)； Contrary to frexp, it is known that x and p find f.
8. Rounding and rounding
double modf (double，double *)； Returns the integer part of a parameter through a pointer, and returns the decimal part.
double fmod (double，double)； Returns the remainder of the division of two parameters.
9. Others
Double sea waves (double x, double y); Given the length of two right-angled sides of a right-angled triangle, find the length of the hypotenuse.
Double ldexp(double x, int exponent); Calculate x * (the exponential power of 2)
double poly(double x，int degree，double coeffs[])； Computational polynomial
Int matherr (structural abnormality * e); Mathematical error calculation processor
Source: C&C++Code Capsule
References:
Math.h-Baidu Encyclopedia