Smooth g Linear smooth (F8)
Averages the Yvalue of every data point with its neighbours. First you have to define the width. The width is the number of data points on either side that will be averaged into the current data point. So a width of 1 means that 3 data points are averaged into one: the center data point, the point left to it, and the point right to it. A width of 2 means 5 data points are averaged, and so on. The source points are taken from the original plot, not the already processed plot. With a width of 2 the algorithm would be like this:
X_{new,i} = X_{old,i }; Y_{new,i} = (Y_{old,i2 }+ Y_{old,i1} + Y_{old,i} + Y_{old,i+1} + Y_{old,i+2}) / 5 
This way, the number of data points of a plot doesn't change, neither does the X value of each data point. Only the Y values are averaged.

Smoothing part of a plot
If you draw a rectangle before selecting the smooth command, only the part of the plot that falls within the rectangle is smoothed. This can be useful if you want to keep a jump in your plot intact, while smoothing the rest of it.
