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Bug or my mistake?
Publié : dim. nov. 20, 2022 11:03 pm
par XcasEngGuy
I am trying to work with differential equations and found this:
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It appears the integrate function can only integrate dy/dt back to y but not d2 y/dy2 back to dy/dt.
Matt
Re: Bug or my mistake?
Publié : lun. nov. 21, 2022 3:45 am
par belanger
Also, it doesn't integrate dy/dt back to y if it is entered as
diff(y(t),t).
If you enter
eq1 := diff(y(t),t,1)
then again
int(eq1,t)
returns undef.
Oddly, perhaps,
diff(y(t),t,1)
returns
diff(y(t),t,1)
I expected
diff(y(t),t)
Jay
Re: Bug or my mistake?
Publié : lun. nov. 21, 2022 11:54 pm
par XcasEngGuy
It appears that any diff command with 3 arguments won't integrate back. int(diff(y(t),t),t) seems to work for me.
cygwin xcas
xcas 1.9.0-29 (c) 2000-18
Win 10 22H2
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Re: Bug or my mistake?
Publié : jeu. nov. 24, 2022 1:09 pm
par parisse
Well, Xcas is not really implemented for solving these kinds of integrals, it expects defined symbolic argument. I'm able to fix these simple examples, but integration by part for example will not work.
Re: Bug or my mistake?
Publié : ven. nov. 25, 2022 6:41 pm
par XcasEngGuy
Fixing these simple examples would help me a lot.
Matt
Re: Bug or my mistake?
Publié : ven. janv. 06, 2023 5:21 pm
par XcasEngGuy
Thank you, works great now.