function logcdf( x ) {
		if ( isnan( x ) ) {
			return NaN;
		}
		if ( x <= a ) {
			return NINF;
		}
		// Case: x > a
		if ( x <= c ) {
			return ( 2.0 * ln( x - a ) ) - ln( denom1 );
		}
		// Case: x > c
		if ( x < b ) {
			return ln( 1.0 - ( pow( b - x, 2.0 ) / denom2 ) );
		}
		// Case: x >= b
		return 0.0;
	}
Evaluates the natural logarithm of the cumulative distribution function (CDF) for a triangular distribution.

@private
@param {number} x - input value
@returns {number} evaluated logCDF

@example
var y = logcdf( 2.0 );
// returns <number>