function gamstar( x ) {
	if ( x >= 3.0 ) {
		return exp( stirling(x) );
	}
	if ( x > 0.0 ) {
		return gamma(x) / ( exp( -x + ( ( x-0.5 ) * ln(x) ) ) * SQRT_TWO_PI );
	}
	// Case: x <= 0.0
	return FLOAT32_MAX;
}
Computes the regulated gamma function.

@private
@param {number} x - input value
@returns {number} function value