Solving Definite Integrals issues with SMath/Maxima

Solving Definite Integrals issues with SMath/Maxima - Solving Definite Integrals issues with SMath/Maxima - Messages

#1 Posted: 7/21/2024 11:10:13 AM
Lasith De Silva

Lasith De Silva

0 likes in 1 posts.

Group: User

Hello SMath Forum,

I'm a relatively new user to SMath and am still figuring out most of its functionality and quirks. For the attached worksheet I am working through three energy transfer calculations for human discharge assessments, all calculations involve solving definite integrals over a defined limit. When defining over the time period of (0,0.000001) I am getting answers magnitudes smaller than expected, the answers expected are shown below (last page of document) and the parameters/constants and base formulas used to derive the SMath worksheet are also referenced below:

Capacitive Discharge - Example Calcs.pdf (766 KiB) downloaded 62 time(s).

The SMath working calculation sheet is here, I feel I've exhausted many different options to try and debug any issues with the calculations but I cannot find anymore alternatives:

Capacitive Discharge -TEMPLATE Case - Solve_1 - Copy.sm (48 KiB) downloaded 57 time(s).

What's also confusing to me, when defining a longer time integral, the answer is changing? Understanding the function after the initial transient period is mostly a steady-state sinuisoidal, I expect the positive/negative peaks to be cancelling out and not contributing to the area under the curve.. Can some please assist with any functionality I have misinterpreted?

I've been advised to adopt a different engineering package like Matlab/Python (although my coding is not the strongest) and I rather enjoy the GUI of SMath - so if I can solve this quirk here I'd be happy.

Appreciate the community's help!

Cheers,

LADS
#2 Posted: 7/21/2024 3:21:10 PM
Alvaro Diaz Falconi

Alvaro Diaz Falconi

992 likes in 1675 posts.

Group: User

Wrote

... The SMath working calculation sheet is here, I feel I've exhausted many different options to try and debug any issues with the calculations but I cannot find anymore alternatives. ...



Hi. The attached can help you debug your calculations.

Capacitive Discharge -TEMPLATE Case - Solve_1 - Copy.sm (100 KiB) downloaded 54 time(s).

Wrote

... What's also confusing to me, when defining a longer time integral, the answer is changing? Understanding the function after the initial transient period is mostly a steady-state sinuisoidal, I expect the positive/negative peaks to be cancelling out and not contributing to the area under the curve.. Can some please assist with any functionality I have misinterpreted?



The steady-state solution has no limit for t -> infinity: this means, it oscillates (you can see it here, for example). It has a sup and inf limit of oscillation, then in the range of oscillation the integral can take any value between the integral range of oscillation.

Best regards.
Alvaro.
  • New Posts New Posts
  • No New Posts No New Posts