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ComputingCMath.h

cos

Cosine function
+ View other versions (4)

Interface

#include <math.h>
double cos (double x)
long cosl (long double x)
float cosf (float x)

#include <complex.h>
double complex ccos (double complex z)
long double complex ccosl (long double complex z)
float complex ccosf (float complex z)

Description

The cos function computes the cosine of x (measured in radians). It returns a value in the range of -1 to 1.

The complex cosine is defined by

Example:
Example - Cosine function
Workings
#include <stdio.h>
#include <math.h>
int main()
{
  double x = 1.047198;
  double result = cos(x);
  printf("The cosine of %lf is %lf\n", x, result);
  return 0;
}
Solution
Output:

The cosine of 1.047198 is 0.500000

Special Values

cos ( 0 ) returns 1.

cos ( ) returns a NaN and raises the invalid floating-point exception.

Standards

The cos function conforms to ISO/IEC 9899:1999(E).