function boxcoxinv( y, lambda ) {
	if ( isnan( y ) || isnan( lambda ) ) {
		return NaN;
	}
	if ( lambda === 0.0 ) {
		return exp( y );
	}
	return exp( log1p( lambda*y ) / lambda );
}
Computes the inverse of a one-parameter Box-Cox transformation.

@param {number} y - input value
@param {number} lambda - power parameter
@returns {number} inverse of the Box-Cox transformation

@example
var v = boxcoxinv( 1.0, 2.5 );
// returns ~1.6505

@example
var v = boxcoxinv( 4.0, 2.5 );
// returns ~2.6095

@example
var v = boxcoxinv( 10.0, 2.5 );
// returns ~3.6812

@example
var v = boxcoxinv( 2.0, 0.0 );
// returns ~7.3891

@example
var v = boxcoxinv( -1.0, 2.5 );
// returns NaN

@example
var v = boxcoxinv( 0.0, -1.0 );
// returns 1.0

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

@example
var v = boxcoxinv( NaN, 3.1 );
// returns NaN