I hope that almost all of this is self-explanatory.

1. Entering formulas

The three wide fields immediately below the main window are the components of the parametrization. The formula parser knows the following functions: sin cos tan sinh cosh tanh arcsin arccos arctan arcsinh arccosh arctanh exp ln and the following binary operations, with their usual precedence: + - * / ^ You can refer to the constants pi and e by name in your formulas. Use 't' for your parameter; other variable names will be treated as if they are zero.

2. Changing the parameter

The two fields showing '-2' and '2' in the picture below hold the minimum and maximum values of 't', respectively. The round, horizontal slider immediately below them changes the current value of the parameter. The round button next to the 'maximum t' field lets you mark a point to serve as the basepoint for the arc-length calculation.

3. Readouts

'K' and 'T' are curvature and torsion, respectively. 's' is arc-length between the current (white) point and the marked (red) point. The 's' field may be greyed out if arc-length integrals didn't seem to be converging.

4. Adjusting the view

You can click and drag in the main window to rotate the view, and you can Control-Click-and-drag to zoom in and out. The small slider on the right controls the size of any decorations you're currently drawing. The slider at the the very bottom of the screen can be used to increase the number of points used to draw your curve. If your drawing doesn't look smooth, drag this to the right.