Re:Tydlig – Calculator Reimagined for iPad and iPhone
by Someone on Sunday December 15, 2013 @06:48AM
(#6909096)
"It's not like a graphing calculator app is going to be that difficult to program"
It is surprisingly hard to get something that produces reliable plots. It starts with getting something as simple as sin(1/x) or x/(x^2 + 5x + 1) to plot reasonably well, and gets harder from there soon (edit: if you want to complicate things, pick a function that is only defined on some numbers, such as sqrt(x^2 * sin(x^3 - x). Adding a pair of || around subexpressions also complicates things)
For example, at https://www.desmos.com/calculator (one of the top results from a google search) zooming in on sin(1/x) shows a plot that sometimes doesn't go up to 1.0 for values of x close to zero. Its plot is decent, but deceiving.
And you will have to do those well, as the target audience of students encounters such functions every day.
It is surprisingly hard to get something that produces reliable plots. It starts with getting something as simple as sin(1/x) or x/(x^2 + 5x + 1) to plot reasonably well, and gets harder from there soon (edit: if you want to complicate things, pick a function that is only defined on some numbers, such as sqrt(x^2 * sin(x^3 - x). Adding a pair of || around subexpressions also complicates things)
For example, at https://www.desmos.com/calculator (one of the top results from a google search) zooming in on sin(1/x) shows a plot that sometimes doesn't go up to 1.0 for values of x close to zero. Its plot is decent, but deceiving.
And you will have to do those well, as the target audience of students encounters such functions every day.
And the Mac OS X one is Grapher (http://en.wikipedia.org/wiki/Grapher)