click the screenshot for a browser-based demo. (once you calculate a scale, you will not be able to save it unless you download the app.)
this is a simple, geometry-based calculator intended to demystify some of the concepts in just intonation. the boxes correspond to possible notes in a scale, and the vertical lines correspond to positions of equal-temperament tones. these lines are visual guides, and the number of equal-temperament tones per octave is user-adjustable. the ratios become more "complex" (higher value divisor) towards the bottom of the window. to approximate an equal-tempered scale, simply select the number of tones you'd like, select the boxes whose *left* sides most accurately line up with the vertical lines, taking into account the occasional trade-off between simpler ratios and a closer approximation. when you are finished with a scale, you can either clear it by pressing "c" or return it by pressing "r". when the scale is returned, a small text file will be created with the date and time as its title, in the directory of the applet. this file contains the array of ratios you chose using the calculator.
"+" - increase number of vertical bars (tones equal temperament)
"-" - reset number of vertical bars to 2
"c" - clear scale buffer
"r" - return scale buffer, printing to file named with date and time, located in app directory (file io won't work in browser version)
i provide this mostly for didactic purposes, but i also use this personally to obtain some of my scales and i thought it might help other people interested in breaking into microtonal theory.