function randn() {
		var f0;
		var f1;
		var x2;
		var x;
		var u;
		var i;
		var j;
		while ( true ) {
			u = ( 2.0*randu() ) - 1.0;
			i = randi() & LAST_7_BITS_MASK;

			// First try the rectangular boxes...
			if ( abs( u ) < R[ i ] ) {
				return u * X[ i ];
			}
			// If bottom box, sample from the tail...
			if ( i === 0 ) {
				return sampleTail( randu, START_RIGHT_TAIL, u < 0.0 );
			}
			// Is this a sample from the wedges?
			x = u * X[ i ];
			x2 = x * x;
			j = i + 1;
			f0 = exp( -0.5 * ( (X[ i ]*X[ i ]) - x2 ) );
			f1 = exp( -0.5 * ( (X[ j ]*X[ j ]) - x2 ) );
			if ( f1 + (randu()*(f0-f1)) < 1.0 ) {
				return x;
			}
		}
	}
Generates a normally distributed pseudorandom number.

@private
@returns {number} pseudorandom number

@example
var r = randn();
// returns <number>