Plus42 Equations, Preview Release

[Marco Polo]

(03-01-2022 06:32 PM)Thomas Okken Wrote:  For integration, it may help to set ACC, e.g. 1E-4 STO "ACC". If ACC is unset, it defaults to zero, which is maximum precision.

I'll have to look into integration slowness. When integrating an equation where the direct solver can find an explicit inverse, it's supposed to keep the inverse for the duration of the integration, so each point is a simple evaluation, and that should be fast. It's not clear to me yet if there is something wrong with the caching of the generated inverse, or if it's slow because of ACC. I'll look into this tomorrow.

There's currently no way to tell it not to use the direct solver. Maybe there should be a flag to control this?

Regarding extrema: the solver doesn't look for them, it merely reports them if it happens to get stuck on one. The robust way to find extrema is to look for roots of the derivative.

The use of ACC increases enormously the integration speed even with 1e-15 and better accuracy: the integration is instantaneous on an Honor 7x smartphone. Tried with Y=X*0+SIN(X).

A flag or a MODE menu entry could do the trick of forcing numerical solutions.

Extrema: i was not sure if the solver would look for them. That's why I asked.