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Can't solve linear equation involving temperatures with Maxima plug-in
  Rank: Advanced Member Groups: Registered
Joined: 18/10/2020(UTC) Posts: 50 
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Hi, I'm doing some heat transfer calculations and I want to solve a simple equation using Maxima plug-in but the results don't appear and the progress bar is just stuck. Here's the equation that I need to solve:  Do you know what's wrong here ? Is it because of temperature units ? I also attached the SMath file:  Heat sink.sm (14kb) downloaded 10 time(s).
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Rank: Advanced Member Groups: Registered
Joined: 28/08/2014(UTC) Posts: 1,356  Was thanked: 815 time(s) in 516 post(s)
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Hi. Tthe problem seems to be related to the variable name, more specifically, to the apostrophe in Ts'  Best regards Alvaro.
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Rank: Advanced Member Groups: Registered
Joined: 18/10/2020(UTC) Posts: 50
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Originally Posted by: Razonar  Hi. Tthe problem seems to be related to the variable name, more specifically, to the apostrophe in Ts' Best regards Alvaro. Thanks for the reply. That's what I also suspected but it doesn't solve the equation even if I change it to T_s2 or T_2 for instance.  I attached a new file where T_s' is replaced with T_s2 and I still don't get any result from this equation: Heat sink.sm (14kb) downloaded 16 time(s).
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Rank: Advanced Member Groups: Registered
Joined: 28/08/2014(UTC) Posts: 1,356 Was thanked: 815 time(s) in 516 post(s)
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Originally Posted by: EngMath I attached a new file where T_s' is replaced with T_s2 and I still don't get any result from this equation: Heat sink.sm (14kb) downloaded 16 time(s). However the file you attached works fine in my SMath. After Maxima gets stuck in a calculation, you have to close SMath and start the process again to get Maxima working. Heat sink.pdf (43kb) downloaded 14 time(s).As margin comment, remember that for temperature differences it's better to use Delta-K or Delta-C units. Best regards. Alvaro. Edited by user 30 January 2022 18:38:52(UTC)
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 1 user thanked Razonar for this useful post.
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Rank: Advanced Member Groups: Registered
Joined: 18/10/2020(UTC) Posts: 50
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Thanks, the calculation was indeed successful when I reopened this SMath file after saving it. I wonder what causes the problem, apparently it's some small bug.
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Rank: Advanced Member Groups: Registered
Joined: 15/04/2012(UTC) Posts: 1,986  Was thanked: 1124 time(s) in 721 post(s)
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Originally Posted by: Razonar After Maxima gets stuck in a calculation, you have to close SMath and start the process again to get Maxima working.
As margin comment, remember that for temperature differences it's better to use Delta-K or Delta-C units.
Best regards.
Alvaro. I filed the problem in the BTS. You also can restart Maxima using the command MaximaControl("Restart" )=.. in your worksheet or from the menu Insert> Maxima> Settings> Save and Restart BTW, there is no Delta-K unit but for all non-absolute temperature units, indeed quantities indicating state have units like °C and changes or differences have units like Delta°C. There is a section on this in the Handbuch. Next to it is a section on angular velocities, a likewise common pitfall in SMath. BTW, was there a special reason to use LinSolve instead of Solve? |
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1 user thanked mkraska for this useful post.
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Rank: Advanced Member Groups: Registered
Joined: 18/10/2020(UTC) Posts: 50
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Originally Posted by: mkraska I filed the problem in the BTS. Thanks for reporting this bug. Originally Posted by: mkraska BTW, was there a special reason to use LinSolve instead of Solve? No, I use it out of habit. And I suppose that it could be faster for linear equations than Solve (I can be wrong though).
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