odeL returns spurious result for incorrect inputs; should give warning

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:14 Created by danielvolinski on 2018-12-18 07:19:20 Original: https://sourceforge.net/p/maxima/bugs/3511

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load(odes)$

odeL('diff(y,x) - (2 x+3 y + 1)/(4 x+6 y + 1), y, x); => y=matrix([])

Daniel

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:15 Created by aleksasd on 2018-12-19 20:05:37 Original: https://sourceforge.net/p/maxima/bugs/3511/#2605

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Function odeL is only for solving linear differential equation Ly=f with constant coefficients. For solving equation y' = (2 x + 3y + 1)/(4x + 6 y + 1) use contrib_ode or change u=2x+3y. In this case odeL must return "false" or some warning. I'm thinking about updated version of package odes.

Merry Christmas

Aleksas D.

2018-12-18, an, 09:19 Daniel Volinski danielvolinski@users.sourceforge.net rašė:

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• [bugs:#3511] https://sourceforge.net/p/maxima/bugs/3511/ another odeL wrong result*

Status: open Group: None Created: Tue Dec 18, 2018 07:19 AM UTC by Daniel Volinski Last Updated: Tue Dec 18, 2018 07:19 AM UTC Owner: nobody

load(odes)$

odeL('diff(y,x) - (2 x+3 y + 1)/(4 x+6 y + 1), y, x); => y=matrix([])

Daniel

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Attachments:

• https://sourceforge.net/p/maxima/bugs/_discuss/thread/a2b70858e9/2605/attachment/alternate

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:18 Created by danielvolinski on 2018-12-19 20:53:01 Original: https://sourceforge.net/p/maxima/bugs/3511/#54fd

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Thanks Aleksas!

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:22 Created by robert_dodier on 2020-12-23 00:16:45 Original: https://sourceforge.net/p/maxima/bugs/3511/#5958

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• labels: --> share packages, diff eqs, odeL

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:25 Created by robert_dodier on 2020-12-23 00:17:27 Original: https://sourceforge.net/p/maxima/bugs/3511/#2ea5

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• summary: another odeL wrong result --> odeL returns spurious result for incorrect inputs; should give warning

[rtoy]

Imported from SourceForge on 2024-07-07 15:54:29 Created by robert_dodier on 2020-12-23 00:36:07 Original: https://sourceforge.net/p/maxima/bugs/3511/#a1c3

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See also #3510 which is another example.