Here's a little graphing app that I helped one of my friends out with.
I think he'll be OK with me posting this as it's still a work in progress at this stage.
The problem originally encountered was that each point was being drawn close together to create the line, this took a significant amount of time.
I lowered the resolution and drew the points apart but then joined the new point to the previous point to create a continuous line.
Here you will see three waveforms created simultaneously.
Regards,
RandomCoder.