asin - Calculate Arcsine

Syntax

#include <math.h>
double asin(double x);

asin calculates the arcsine of x, in the range -pi/2 to pi/2 radians.

asin returns the arcsine of x. The value of x must be between -1 and 1. If x is less than -1 or greater than 1, asin sets errno to EDOM, and returns a value of 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 arcsine 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 asin\n", x);
   else
      if (x < MIN)
         printf("Error: %lf too small for asin\n", x);
      else {
         y = asin(x);
         printf("asin( %lf ) = %lf\n", x, y);
      }
   return 0;

   /****************************************************************************
      For the following input: 0.2

      The output should be:

      Enter x
      asin( 0.200000 ) = 0.201358
   ****************************************************************************/
}

[Back]

[Next]