### _fasin -- Calculate Arcsine

Format

>     #include <builtin.h>
>     double _fasin(double x);

Language Level: Extension
_fasin calculates the arcsine of x. This function causes the compiler to emit the appropriate 80387 instructions for the calculation of arcsine.

Because it is a built-in function and has no backing code in the library:

- You cannot take the address of _fasin.
- You cannot parenthesize a _fasin function call, because parentheses specify a call to the backing code for the function.

Return Value
_fasin returns the arcsine of x.

Example
This example prompts for a value of 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 <builtin.h>
    #include <stdio.h>

    #define MAX  1.0
    #define MIN -1.0

    int main(void)
    {
       double x;

       printf("Enter x:\n");
       scanf("%lf", &x);

       /* Output error if not in range */
       if (MAX < x)
          printf("Error: %lf too large for asin.\n", x);
       else if (MIN > x)
               printf("Error: %lf too small for asin.\n", x);
            else
               printf("The arcsine of %lf is %lf.\n", x, _fasin(x));
       return 0;

       /************************************************************
          Assuming you enter: 1.0

          The ouput should be:

          The arcsine of 1.000000 is 1.570796.
       ************************************************************/
    }

asin -- Calculate Arcsine
_fcossin -- Calculate Cosine and Sine
_fsin -- Calculate Sine
_fsincos -- Calculate Sine and Cosine
sin -- Calculate Sine
sinh -- Calculate Hyperbolic Sine
<builtin.h>