function arcsine2( a, b ) {
		if (
			isnan( a ) ||
			isnan( b ) ||
			a >= b
		) {
			return NaN;
		}
		return arcsine0( rand, a, b );
	}
Returns an arcsine distributed pseudorandom number with minimum support `a` and maximum support `b`.

@private
@param {number} a - minimum support
@param {number} b - maximum support
@returns {number} pseudorandom number

@example
var v = arcsine2( 0.0, 1.0 );
// returns <number>

@example
var v = arcsine2( 1.0, 0.0 );
// returns NaN