So, I spent the last few days working on GraphSketch, a new, free, online grapher. It’s available at http://graphsketch.com/ . Go check it out for a minute. Try graphing something like “(x-3)(x+10)(x-14)/100” or “tan(pi*x/10)“. I’ll wait.
Done? That’s pretty much it: Enter an equation, choose some settings, and graph it. There are a number of functions you can use to plot, you can save the graphs to use later (in documents, worksheets, etc.), you can create a permanent link to them to share with others, and a few other nice little things (like getting a quick graph by going to an address like http://graphsketch.com/sqrt(x) ). Details on how below.
GraphSketch is mostly written in PHP, with the actual graphing done in gnuplot. Some manipulation is done in PHP before things are passed to gnuplot to account for odd roots, implicit multiplication, and so forth. In gnuplot, I’m using the pngcairo terminal, implemented in the not-yet-released gnuplot 4.3 CVS code (it’s public but not a “stable” release), to get anti-aliased graphs, because aliased graphs (especially with low graph widths) tend to look relatively poor.
So, if you have any questions, comments, or suggestions about GraphSketch, feel free to leave a comment below or email me at andy.schmitz at gmail.com.
Update 05/12: GraphSketch now has delivered over 10,000 graphs.