Comments on: Creating a PHP Graphing Calculator

By: Toni

Toni — Sun, 30 Jan 2011 02:44:51 +0000

You’re almost there – I’m about to update the code above to make use of a scaling global variable, where scale > 1 zooms in, and scale < 1 zooms out. I think it’s right, its been a while since I worked on this so I might have missed something.

By: Ice

Ice — Fri, 28 Jan 2011 01:48:48 +0000

I’m interested in expanding the x and y ranges of your graph…

Getting the additional ticks on the y and x axis is easy:
for ($lcv = 0 ; $lcv < $GLOBALS['width']/2*$scale; $lcv += 50)
for ($lcv = 0 ; $lcv < $GLOBALS['height']/2*$scale; $lcv += 50)

& Converting functions:
pixelsToCart()
$passX = $scale*$passX – $GLOBALS['width'] / 2;
$passY = $scale*$passY + $GLOBALS['height'] / 2;

cartToPixels()
$passX = $GLOBALS['width'] / 2 – $scale*$passX;
$passY = $GLOBALS['width'] / 2 + $scale*$passY;

However, the graph only plots to the original stopping and starting area of the default graph.

By: Joshua

Joshua — Wed, 09 Dec 2009 08:00:02 +0000

I was looking for such script for ages. Thank you.

By: Toni

Toni — Tue, 16 Dec 2008 05:11:54 +0000

Thanks! The code above doesn’t offer changing the range of the plot, but there are some comments in the cartToPixels and pixelsToCart functions that describe using a coefficient to alter the range plotted. By adding a user defined coefficient to each calculation in those two functions, you could zoom in/out on the graph pretty easily.

By: HaXiT

HaXiT — Sat, 13 Dec 2008 01:12:05 +0000

Awesome script! Is there any way to reduce the range in which it plots the graph?