code: function cdf( x, a, b, c ) {
  	var denom1 = ( b - a ) * ( c - a ),
  		denom2 = ( b - a ) * ( b - c );
  
  	if ( x !== x ) {
  		return NaN;
  	}
  	if ( x <= a ) {
  		return 0;
  	}
  	// Case: x > a
  	if ( x <= c ) {
  		return pow( x - a, 2 ) / denom1;
  	}
  	// Case: x > c
  	if ( x < b ) {
  		return 1 - pow( b - x, 2 ) / denom2;
  	}
  	// Case x >= b
  	return 1;
  }
docs: CDF // 
  FUNCTION: cdf( x, a, b, c )
  Evaluates the cumulative distribution function (CDF) for a Triangular distribution with lower limit `a` and upper limit `b` and mode `c` at a value `x`.
  
  @param {Number} x - input value
  @param {Number} a - lower limit
  @param {Number} b - upper limit
  @param {Number} c - mode
  @returns {Number} evaluated CDF