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asin() Calculate Arc Sine
#include <math.h>
double asin(x); Arc sine (in radians)
double x;
asin() returns the arc sine of 'x' in radians. 'x' must be in the
range -1.0 to 1.0; the value returned is in the range -./2 to ./2.
Returns: The arc sine of 'x'. If 'x' < -1.0 or > 1.0, then
matherr() is called with a DOMAIN error; 'errno'
(defined in <errno.h>) is set to EDOM (defined in
<math.h>); a domain error message is printed to
'stderr'; and 0.0 is returned.
Notes: You can modify error handling with the matherr()
routine.
-------------------------------- Example ---------------------------------
The following statements continue printing the arc sines of the
values in an array until a DOMAIN error occurs.
#include <math.h> /* for asin() and EDOM */
#include <stdio.h> /* for printf() */
#include <errno.h> /* for errno */
/* the value 3.141 will cause an error */
double sines[6] = {0.707, 0.0, 1.0, -1.0, 3.141, -0.2};
main()
{
double arc_sine;
int i;
errno = 0;
for (i = 0; !errno && i < 6; i++) {
arc_sine = asin(sines[i]);
if (errno == EDOM) /* an error is also printed to stderr
*/
printf("DOMAIN error in asin()\n");
printf("arc sine of %f = %f radians\n", sines[i],
arc_sine);
}
}
See Also:
matherr()
sin()
sinh()
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