Crash when Solve for Integral with 15C

[Gerson W. Barbosa]

(09-02-2017 08:34 PM)Dieter Wrote:  

(09-02-2017 08:14 PM)rprosperi Wrote:  Ok, I just have to ask... why 216?

The integration limits have to be substituted, i.e. they are now 0³ = 0  and  6³ = 216.

Yes, because of the variable change suggested by you, BTW, as an attempt to improve the execution time.

I did

u=x^3 -> x=u^(1/3)

du/dx=3*x^2 -> dx=du/(3*x^2)

-> Integ(e^x^3 dx, 0, 6) = 1/3*Integ(e^u/u^(2/3), 0, 216)

Interestingly the speed improvement on the 34C, as reported by AndyGer, and the HP-41CV (w/ Advantage ROM) is about only 20%, not so good as the 50% I had observed on the iOS HP-15C emulator by HP.

Gerson.

PS: W|A gives a closed form solution for the latter in terms of Gamma and Incomplete Gamma functions:

1/6(1+i*sqrt(3))*(Gamma(1/3)-Gamma(1/3,-6^3))

Unfortunately the Incomplete Gamma implementation on the WP34S won't handle these arguments.

PPS: Edited to fix a typo per Bob Prosperi's observation below.

PPPS: Edited again to add a 1/3 constant I had missed when transcribing my own hand-written note, as spotted by Pekis ahead.