Thanks for the tip. It works great. Two more similiar questions: 1) For the open circle, is there a way to fill in its area with white space so the function passing through it is not visible? 2) How is solid colored dot made? Can the radius of the point symbol be changed, perhaps??? Thanks a lot!!

Thanks for the tip on vertical lines using plot([2,y,y=-2..2]); However how does one control the linestyle of these lines? I want a verticle line that is dashed. I have tried: plot([2,y,y=-2..2],linestyle=dash); but it didn't work. What is odd is that other options such as "style" and "color" do work, but for some reason "linestyle" doesn't. plot([2,y,y=-2..2],style=point); WORKS plot([2,y,y=-2..2],color=yellow); WORKS plot([2,y,y=-2..2],linestyle=dash); DOES NOT WORK Any suggestions or completely other alternative? FYI: I am making epsilon-delta plots. Thanks in advance.