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Offline Saviind  
#1 Posted : 26 November 2023 03:33:51(UTC)

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Hello All,
I have four unknowns in three linear equations. In this setup, can the FindRoot function get values for these variables?
I tried the same in MathCAD and could get the solution, but it is not working in Smath.
Can someone guide me, please?
Are there other possible solving methods for handling such equations with 6 or 8 unknowns?
Trial.sm (38kb) downloaded 12 time(s).[a Trial.sm (38kb) downloaded 12 time(s).ttach]48521[/attach] Trial.sm (38kb) downloaded 12 time(s).
Best Regards
Offline overlord  
#2 Posted : 26 November 2023 05:14:54(UTC)

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Usually al_nleqsolve() is more capable at this kind of situations.
Also your functions shouldn't have boolean operations.


Offline mkraska  
#3 Posted : 26 November 2023 05:40:21(UTC)

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Solve() from the Maxima plugin can handle under-determined systems of equations. In such cases, the solution contains a free variable. The name changes every time the sheet is recalculated. If you want to rely on that name, insert a MaximaControl("restart" ) command to reset the Maxima session and the counter.

2023-11-25 16_32_27-SMath Solver - [Trial.sm_].png
Trial_Kr.sm (42kb) downloaded 8 time(s).
Martin Kraska

Pre-configured portable distribution of SMath Studio: https://smath.com/wiki/SMath_with_Plugins.ashx
Offline Razonar  
#4 Posted : 30 November 2023 08:08:00(UTC)

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Originally Posted by: Saviind Go to Quoted Post
... I tried the same in MathCAD and could get the solution, but it is not working in Smath....

Hi. Can you share the Mathcad result? This page is the help for matlab techniques for handling underdetermined systems: https://www.mathworks.co...r-equations.html#bt7ov7u

Writing the system as a linear one, SMath have some functions for work with those systems, like this one


Trial.sm (62kb) downloaded 7 time(s).

Best regards.
Offline Jean Giraud  
#5 Posted : 02 December 2023 01:40:17(UTC)
Jean Giraud

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For your f(x,y,z) ... I get two sets of solved [x,y,z].
Smath solves the Mathsoft example, 4 unknowns.
Smath Butller is lot more advanced/difficult.

Solve FindRoot f(x,y,z) ITERATIVE.sm (104kb) downloaded 9 time(s).
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