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Synopsis:
    #include <math.h>
    double asin( double x );

Description:
    The asin function computes the principal value of the arcsine of x.  A
    domain error occurs for arguments not in the range [-1,1].

Returns:
    The asin function returns the arcsine in the range [-P/2,P/2].  When the
    argument is outside the permissible range, the  matherr function is
    called.  Unless the default  matherr function is replaced, it will set
    the global variable  errno to  EDOM, and print a "DOMAIN error"
    diagnostic message using the  stderr stream.

Example:
    #include <stdio.h>
    #include <math.h>

    void main()
      {
        printf( "%f\n", asin(.5) );
      }

    produces the following:

    0.523599

Classification:
    ANSI

Systems:
    Math

See Also:
    acos, atan, atan2, matherr