Format
#include <math.h> double asin(double x);
Language Level: ANSI
Threadsafe: Yes.
Description
The asin() function calculates the arcsine of x, in the range -&pi./2 to &pi./2 radians.
Return Value
The asin() function 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, the asin() function sets errno to EDOM, and returns a value of 0.
Example that uses asin()
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 ); } } /**************** Output should be similar to ****************** Enter x asin( 0.200000 ) = 0.201358 */
Related Information
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