Function app — Signed Area

[cdmackay]

Helping my daughter with her homework gave me the chance to play with some of the Function app's Plot functions, which I'd not used before.

The Signed Area function is great, which gives the area under one function and above another (or the X-axis) between two points.

However, one thing I thought could be easier, would be a quicker way to select the two end-points as intersection points of the functions. That's because the Function app's Results vars only include the last intersection point found (Isect).

Methods I've used so far include:

• Finding the first intersection point, then using Copy-X to put it on the clipboard. Then find the second intersection point. Then start Signed Area, using Paste to set the From point, and Vars/Results/Isect to set the To point. This works, but seems a little fiddly.

• Finding the intersection points and, for each, drop to the cmdline and store the first Vars/Results/Isect in A, the second in B. Then Signed Area, and set the points to A and B (by name). Again fiddly.

• Getting rough X values for the intersection points visually (e.g. 1–2), then finding the signed area from the cmdline, with e.g AREA(F1, F2, ISECT(F1, F2, 1), ISECT(F1, F2, 2)). This has the drawback of not showing the area visually, which is a useful teaching feature.

What might be nice would be the ability to set the From and To points by "snapping" the cursor to points of interest, like intersection points.

Alternatively, to store more than just the single last result of a function, e.g. store the last n results, so that you may select from them, or as a list.

Does anyone have any other tips/tricks for this sort of thing?


Anyway, that's just a quibble; what struck me was the wonder of being able to seamlessly switch between different views, Symbolic, Numeric, Plot, Vars, Toolbox, cmdline, and Help, without getting lost, or having to read the paper/PDF manuals, and it all Just Works. That's a fine piece of design, for sure. And that's without even being able to move/access data between Apps, which I've yet to explore.

…

And my daughter is now desperate to get her hands on the Prime