asin(p1)
public
Computes the arc sine of x. Returns -{PI/2} .. {PI/2}.
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static VALUE
math_asin(VALUE obj, VALUE x)
{
double d0, d;
Need_Float(x);
d0 = RFLOAT_VALUE(x);
/* check for domain error */
if (d0 < -1.0 || 1.0 < d0) domain_error("asin");
d = asin(d0);
return DBL2NUM(d);
}