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asin |
Portability: | ISO/ANSI C conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
DIAGNOSTICS | |
EXAMPLE | |
RELATED FUNCTIONS | |
SEE ALSO |
SYNOPSIS |
#include <math.h> double asin(double x);
DESCRIPTION |
asin
computes the trigonometric arc sine of the value
x
. The arc sine function is the inverse of the sine function and is
expressed by the following relation:
x
is in the closed interval
[-1.0,1.0] .
RETURN VALUE |
asin
returns the principal value of the arc sine of the argument
x
, provided that this value is defined and computable. The return
value is a double precision floating-point number in the closed interval [-
/2, /2] radians.
DIAGNOSTICS |
asin
returns 0.0 if the value of its argument is larger than 1.0 or smaller than -1.0.
The run-time library writes an error message to the standard error file (
stderr
) in this case.
If an error occurs in
asin
, the
_matherr
routine is called.
You can supply your own version of
_matherr
to suppress the diagnostic message or modify the value returned.
EXAMPLE |
This example computes pi as 4 times the arc sine of the square root of 0.5:
#include <math.h> #include <stdio.h> main() { double pival, value; value = .500; pival = 4 * asin(sqrt(value)); printf("4 * asin(sqrt(%f)) = %f\n",value,pival); }
RELATED FUNCTIONS |
SEE ALSO |
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