Problem with integral on WP 34s

[Albert Chan]

(09-08-2021 06:12 AM)pascal_meheut Wrote:  I get 0 on the iPad but the correct value on the OSX emulator. The source code should be the same as far as I know (and I should know as I wrote them) but the firmware version is different.
Unfortunately, I do not have the programming environment nor the time to debug it.

There might not be a bug to debug.
Most integration routine assumed no singularity within integral limits.
(this is especially true for double-exponential integration, with sample points mostly on the edges)

Convergence is based on previous estimate, not true result.
(if we do know true result, there is no need to integrate ...)

If we are lucky, "converged" result is close to true result.
Unfortunately, we don't know how good the result really is.
If not, routine may give up (thus the 0.0 result)

We should break up integral to peices. In this case, surd(x,3) is odd function:

∫(1/surd(x,3), x=-2 .. +3) = ∫(x^(-1/3), x=+2 .. +3) = preval(x^(2/3)/(2/3), 2, 3) ≈ 0.7390