code: function CubicInterpolant( parameterPositions, sampleValues, sampleSize, resultBuffer ) {
  
  	Interpolant.call( this, parameterPositions, sampleValues, sampleSize, resultBuffer );
  
  	this._weightPrev = - 0;
  	this._offsetPrev = - 0;
  	this._weightNext = - 0;
  	this._offsetNext = - 0;
  
  }
docs: Fast and simple cubic spline interpolant.
  
  It was derived from a Hermitian construction setting the first derivative
  at each sample position to the linear slope between neighboring positions
  over their parameter interval.
  
  @author tschw