I think I had learned this before and forgot it. It took me 15 minutes to figure out how to do it and so I thought it made the perfect post for this blog so I could find it again if I needed it.

For a publishing project upon which I am working I needed to graph the cost in dollars of a cell phone plan versus the months from 1 to 24. The equation was C = 79.99 + 94.99m. I wanted to make this a discrete graph rather than a continuous graph because the almost always the consumer pays for a full month and not a fraction of a month.

I set up my axes in Winplot to give an appropriate scale. Then I went to the equation menu and picked point. I entered a as the value for x. I entered 79.99 + 94.99*a for y. The equation inventory popped up.

I clicked on family and for the value a I entered a starting value of 1, an ending value of 24 and 23 steps.