lib/dRanNormalTail.js
function dRanNormalTail( dMin, iNegative, rand ) {
	var x, y;
	do {
		x = ln( rand() ) / dMin;
		y = ln( rand() );
	} while ( -2 * y < x * x );
	return iNegative ? x - dMin : dMin - x;
}
function dRanNormalTail( dMin, iNegative, rand ) {
	var x, y;
	do {
		x = ln( rand() ) / dMin;
		y = ln( rand() );
	} while ( -2 * y < x * x );
	return iNegative ? x - dMin : dMin - x;
}
function dRanNormalTail ( dMin , iNegative , rand ) { var x , y ; do { x = ln ( rand ( ) ) / dMin ; y = ln ( rand ( ) ) ; } while ( - 2 * y < x * x ) ; return iNegative ? x - dMin : dMin - x ; }
NORMAL TAIL // 
FUNCTION dRanNormalTail( dMin, iNegative, rand )
Transform the tail of the normal distribution to
the unit interval and then use rejection technique
to generate standar normal variable.
Reference:
Marsaclia, G. (1964). Generating a Variable from the Tail
of the Normal Distribution. Technometrics, 6(1),
101–102. doi:10.1080/00401706.1964.10490150

@param {Number} dMin - start value of the right tail
@param {Boolean} iNegative - boolean indicating which side to evaluate
@param {Function} rand - random number generator
@returns {Number} standard normal variable
NORMAL TAIL // FUNCTION dRanNormalTail ( dMin iNegative rand ) Transform the tail of the normal distribution to the unit interval and then use rejection technique to generate standar normal variable . Reference : Marsaclia G . ( 1964 ) . Generating a Variable from the Tail of the Normal Distribution . Technometrics 6 ( 1 ) 101–102 . doi : 10 . 1080 / 00401706 . 1964 . 10490150