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This week's quiz idea provided and written by Martin DeMello.

## Equation Graphing (#176)

Back when the world was shiny and new, and BBC Basic my language of
choice and necessity, one of the fun little programs I wrote was a
simple equation grapher. Two things that made it simple were (i) the
ever-useful EVAL function, and (ii) the almost trivial ability to pick
a colour and a pair of coordinates and put a friendly glowing pixel
onto the screen. Instant gratification writ large. Well, anything that
Basic can do, Ruby should be able to, so your task this week is to
whip out your favourite graphics toolkit or library and write a
program that

1. Asks for a function of one variable, x
2. Asks for the region of the graph to display (xmin, xmax, ymin, ymax)
3. Plots the graph

You can trust the user to input a syntactically correct function, but
don't forget that it might behave badly for certain values of x (e.g.
1/x where x=0). Style points for making the main loop look trivial :)

Here's a neat little online grapher you can use to visually check your
output: <http://www.walterzorn.com/grapher/grapher_e.htm>.



-- 
Matthew Moss <matthew.moss / gmail.com>