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 KiB) downloaded 58 time(s).
File not found.File not found.

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 KiB) downloaded 67 time(s).

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 KiB) downloaded 61 time(s).
Inst_Colebrook Pipe Data.sm (59 KiB) downloaded 53 time(s).
Solve Given_Find [UN Frobenius C1, C2].sm (71 KiB) downloaded 57 time(s).
FindRoot_test_0 Revisit.sm (41 KiB) downloaded 58 time(s).
Inst_Colebrook Pipe Data [Solve Node Flow].sm (149 KiB) downloaded 57 time(s).
Inst_Colebrook.sm (191 KiB) downloaded 60 time(s).
Inst_Colebrook.sm (191 KiB) downloaded 53 time(s).

Dear Jean,

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

Thank you!

MS