Threshold shade

Obtains x and y data to be used with the matlab 'fill' command. The filled areas are above a positive threshold or below a negative threshold, or both. The filled areas are bound between start and stop points on the x-axis as defined by the user.

A full description of the function, input and output variables, and example usage can be found within the function's starting comments. Examples on how to use the output data is also included in the function (look in the 'Plotting' section at the end of the function).

Please feel free to get in contact for suggested improvements and/or the detection of bugs.