Syntax
#include <math.h> double acos(double x);Description
acos calculates the arccosine of x, expressed in radians, in the range 0 to the value of pi.
acos returns the arccosine of x. The value of x must be between -1 and 1 inclusive. If x is less than -1 or greater than 1, acos sets errno to EDOM and returns 0.
This example prompts for a value for x. It prints an error message if x is greater than 1 or less than -1; otherwise, it assigns the arccosine of x to y.
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAX 1.0
#define MIN -1.0
int main(void)
{
double x,y;
printf("Enter x\n");
scanf("%lf", &x);
/* Output error if not in range */
if (x > MAX)
printf("Error: %lf too large for acos\n", x);
else
if (x < MIN)
printf("Error: %lf too small for acos\n", x);
else {
y = acos(x);
printf("acos( %lf ) = %lf\n", x, y);
}
return 0;
/****************************************************************************
For the following input: 0.4
The output should be:
Enter x
acos( 0.400000 ) = 1.159279
****************************************************************************/
}
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