Solve() function with units

#1 Posted: 1/27/2023 8:51:24 AM

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Hello,

I can't find the error. I want to solve a simple linear equation for a static problem. But with the solve() function i can't enter units.

it says not real roots.

Thanks for help

#2 Posted: 1/27/2023 11:19:01 AM

Jean Giraud

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Wrote
I can't find the error. I want to solve a simple linear equation for a static problem. But with the solve() function I can't enter units.

Generally, solve blocs aren't units compatible.
Attach the document for possible doctoring.

#3 Posted: 1/27/2023 12:11:37 PM

Thomy

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Hello
You can find the file in the attachment

#4 Posted: 1/27/2023 12:27:22 PM

Alvaro Diaz Falconi

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There is no "solve block" there. For the real ones there is a plugin. In any case, there is a function to find roots, which is compatible with the use of units, you just have to know how to use it and in what cases. For this function, the roots function seems more suitable instead of solve. Try with this, for example

Best regards.
Alvaro

#5 Posted: 1/27/2023 12:39:17 PM

Thomy

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Doesn't work. The File is in the attatchment.

Thanks you very much

#6 Posted: 1/27/2023 12:55:43 PM

Alvaro Diaz Falconi

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Wrote
Doesn't work. The File is in the attachment. ...

Hi. I can't find the file.

Best regards.
Alvaro.

#7 Posted: 1/27/2023 1:00:31 PM

Thomy

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Fixpunkte LIWA.sm (4 MiB) downloaded 53 time(s).

#8 Posted: 1/27/2023 1:04:41 PM

Alvaro Diaz Falconi

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Fixpunkte LIWA.sm (4 MiB) downloaded 53 time(s).

Hi. It works in my environment. Try with F9 for update the calculation.

Best regards.
Alvaro.

#9 Posted: 1/27/2023 2:37:16 PM

Jean Giraud

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Doesn't work. The File is in the attatchment.

NO file attached !!!

#10 Posted: 1/27/2023 7:20:52 PM

Martin Kraska

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In your initial post, just replace solve() by Solve(). This requires the Maxima Plugin being installed.
It is a symbolic solver, which has generic unit handling, i.e. the unit of the result is determined by the solver.

An alternative is the FindRoot function, where you have to provide an initial guess (starting point for the numeric solver) and the result is automatically assigned to the variable.

The maxima solver returns an equation variable=solution, which can be converted into an assignment by the Assign() function. More details to be found in the handbook (Google SMath Handbuch).

2023-01-27 23_20_25-SMath Solver - [Fixpunkte LIWA.sm_].png

Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx

#11 Posted: 2/3/2023 12:27:57 PM

Thomy

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How can i install the MaximaPlugin. Do i have to integrate the maxima folder in the plugin subfolder from SMath?

#12 Posted: 2/3/2023 3:20:16 PM

Martin Kraska

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Wrote
How can i install the MaximaPlugin. Do i have to integrate the maxima folder in the plugin subfolder from SMath?

Follow the link in my signature (points to the wiki). There you find instructions.

Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx

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Solve() function with units - Solve() with units - Messages