Can I put markers on only some of the points in my plot?

There is no command to plot only every other marker, or every third marker, or every nth marker. However, you can accomplish this by using the following command, assuming you have your X-data stored in XVec and your Y-data stored in YVec:

plot(XVec(1:2:end),YVec(1:2:end), '+')

This command will plot every other point in your data using the + marker. Change the 2 in the statement to a 3 to plot every third point:

plot(XVec(1:3:end),YVec(1:3:end), '+')

or to a 4 to plot every fourth, etc:

plot(XVec(1:4:end),YVec(1:4:end), '+')

To plot a line with every fourth marker present, you can use the following code:

plot(XVec,YVec)

hold on

plot(XVec(1:4:end),YVec(1:4:end), '+')

hold off