DSPLOT - downsampled plot

This version of "plot" will allow you to visualize data that has very large number of elements. Plotting large data set makes your graphics sluggish, but most times you don't need all of the information displayed in the plot. Your screen only has so many pixels, and your eyes won't be able to detect any information not captured on the screen.
This function will downsample the data and plot only a subset of the data, thus improving the memory requirement. When the plot is zoomed in, more information gets displayed. Some work is done to make sure that outliers are captured.

Syntax:
dsplot(x, y)
dsplot(y)
dsplot(x, y, numpoints)

Example:
x =linspace(0, 2*pi, 1000000);
y1=sin(x)+.02*cos(200*x)+0.001*sin(2000*x)+0.0001*cos(20000*x);
dsplot(x,y1);