casin

Arc sine function

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Contents

Interface
Description
Special Values
See Also
Standards
Compatibility
Page Comments

Interface

#include <math.h>double  asin (double x)
long  asinl (long double x)
float  asinf (float x)

#include <complex.h>complex  asin (complex x)
double complex  casin (complex x)
float complex  casinf (float complex x)
long double complex  casinl (long double complex x)

Description

The asin function computes the principal value of the arc sine of x in the range $\inline [-1,1]$ , returning a value in the interval $\inline [-\pi/2,+\pi/2]$ . The arc sine is also often called the inverse sine and is denoted by $\inline \sin^{-1}(x)$ .

The complex inverse sine is defined by:

$\mathrm{asin}(x) = -i \log\left (i x + \sqrt{1-x^2} \right )$

(2)

Example:

Example - Arc sine function

Workings

#include <stdio.h>
#include <math.h>
int main(void)
{
  double result, x = 0.289;
  result = asin(x);
  printf("The arc sin of %lf is %lf\n", x, result);
  return 0;
}

Solution

Output:

The arc sin of 0.289000 is 0.293182

Special Values

asin ( 0 ) returns 0.

asin ( x ) returns a NaN and raises the invalid floating-point exception for |x| > 1.

Standards

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

Compatibility

	DOS	UNIX	Windows	ANSI C	C++ only
asinl	•		•
asinf	•	•	•
Real asin	•	•	•	•
Complex asin	•		•		•
Complex casin		•			•

double	`asin` (double x)
long	`asinl` (long double x)
float	`asinf` (float x)

complex	`asin` (complex x)
double complex	`casin` (complex x)
float complex	`casinf` (float complex x)
long double complex	`casinl` (long double complex x)