code: public void scaleYResolution(double factor) {
          this.y_resolution = Math.max(1.0, this.y_resolution * factor);
          updateYResolution();
          updateUpperYValue();
          updateCanvas(true);
      }
docs: Scales the resolution on the y-axis by the given factor and updates the
  canvas. The y-resolution must not be lower than 1.
  
  @param factor
  factor the y_resolution will be scaled by