Hi
I need a help for "FindRoot" function.(See attached file)

Also I got an error sample file(Inst_Colebrook_pipe_data.sm) which was downloaded from this forum.

Please, guide me to solve this error.

Novice

FindRoot_test_0.sm (40,44 КиБ) скачан 238 раз(а).
Файл не найден.Файл не найден.

Hello [userlink]Novice[/userlink]

An important thing is that Q1 must be undefined while you define the system of equations - and as for now even when you call FindRoot; there is a buil-in function Clear(...) for this.

Secondly as for now when there are numerical functions involved in the evaluation of the unknowns this plugin has issues (in this case the issue is in if(f(Q1), that can be replaced by cases(...), however the algorithm then fails to solve for the given initial guess);

FindRoot_test_0.sm (38,94 КиБ) скачан 239 раз(а).

I'm working to improve both these things.

Wrote

Please, guide me to solve this error.

You MUST draw the diagram first !
Get inspired from NDTMA Collab [Colebrook Node].

Comments:

1. The "GivenFind" solver does not necessarily solves.
I have recollection solving for 22 variables in Mathcad 11.
It was necessary to constrain some variables, and this was
possible from some existing models, in fact: just refining
within the "solvability" of the system.

2. You have 7 'Q' indexed: that's not viable.
Instead: Q1, @2, Q3, ... Q7

3. Please rework the project to ease reading/understanding.

Jean

Inst_Colebrook MOODY.sm (21,92 КиБ) скачан 245 раз(а).
Inst_Colebrook Pipe Data.sm (59,97 КиБ) скачан 221 раз(а).
Solve Given_Find [UN Frobenius C1, C2].sm (71,34 КиБ) скачан 189 раз(а).
FindRoot_test_0 Revisit.sm (41,94 КиБ) скачан 226 раз(а).
Inst_Colebrook Pipe Data [Solve Node Flow].sm (149,29 КиБ) скачан 193 раз(а).
Inst_Colebrook.sm (191,95 КиБ) скачан 232 раз(а).
Inst_Colebrook.sm (191,95 КиБ) скачан 220 раз(а).

Dear Jean,

Thank you very much for your advice and examples
It is helpful to me.

Thank you!

MS