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Offline omorr  
#221 Posted : 29 October 2016 21:29:16(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
That's not a bug Radovan:

=>...For the free finding solutions, IC must be either 0 or 1
[1 to releive from "divide by zero"]<= ... {previous message}
Maybe you are not up to date vs Davide ?

Jean


I was using SMath 0.98.6128 an NonlinerSolver 1.1.6099.14159

Regards,
Ra
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Offline omorr  
#222 Posted : 16 May 2017 19:20:27(UTC)
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Originally Posted by: Davide Carpi Go to Quoted Post
Thank you guys, these examples are very useful to fix the bugs in this plugin Good

I'm working to a new version of the code, almost totally refactored.
Looking at your examples seems there are several things to fix in my preprocessor; with some tweak, it is able to solve it.

2016-10-24 18_27_07-SMath Studio - [FindRoot.sm_].png

now I just have to find some consistant way to make it working always Crazy


Davide, any progress about this plugin and its new version?

Regards,
Radovan
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Offline Davide Carpi  
#223 Posted : 16 May 2017 21:00:19(UTC)
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Originally Posted by: omorr Go to Quoted Post
Davide, any progress about this plugin and its new version?

Regards,
Radovan


Hello Radovan! Good

More or less, I'm trying to make it working on the numerical functions (those containing if/else, etc...), requires some more refactoring, I'll see if I can focus on this plugin in the coming weeks...
Best regards,

Davide

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Offline Jean Giraud  
#224 Posted : 17 May 2017 05:32:46(UTC)
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Maybe, I don't understand much in there ?

Jean

Page1 Unknown Solve.sm (31kb) downloaded 35 time(s).
Offline omorr  
#225 Posted : 17 May 2017 16:11:59(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
Maybe, I don't understand much in there ?

Jean

Page1 Unknown Solve.sm (31kb) downloaded 35 time(s).

Helo Jean,

You should define f(x) not f(u). See the file, please. Was that your question?

Page1%20Unknown%20Solve-2-corr.sm (35kb) downloaded 30 time(s).

Regards,
Radovan
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Offline Jean Giraud  
#226 Posted : 19 May 2017 14:55:47(UTC)
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Hello Radovan,

Example in context works fine for me. Integrator is now "scalar" 6179.
It enables the Fourier Quantum double integral, though awfully slow.
For N =31, CoC takes > 2hrs [Win 7 1.6 GHz]. ∫(x) comes from Maple.

Jean

Integral Curve Nuance.sm (27kb) downloaded 33 time(s).
Offline Alex M.  
#227 Posted : 13 April 2018 19:13:37(UTC)
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Hello SMath Community, need some help with findroot() function.

I wrote a formula (biaxial bending in a column) to calculate unknown input loads based on known response. A key to practical use of the formula is to solve for unknown response based on known input loads (backwards of what formula does). When using findroot() for this purpose i run into error:
FidRoot-CustomFormulaSolution.sm (538kb) downloaded 20 time(s).
FidRoot-CustomFormulaSolution.png
What am i doing wrong?

Thanks!
Offline Davide Carpi  
#228 Posted : 13 April 2018 19:36:36(UTC)
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FindRoot, as well as other solvers of NS plugin, is not friend of eval, if/else or in general anything that requires a strict numerical evalution to be performed... that's a thing I'm working on (long overdue, I know...)
Best regards,

Davide

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Offline mkraska  
#229 Posted : 12 December 2018 02:14:58(UTC)
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I don't know when these changes happened but my current observation of Findroot's behaviour seems to be different from earlier versions:

  • Just evaluate: displays result vector and executes embedded assignment

  • Assign and evaluate in the same region: Error (symbolic evaluation reveals that the expression isn't executed but just stored as if it was inside line())

  • Assign and evaluate in separate regions: displays result vector and executes embedded assignment upon display.

  • Assign wrapped in eval() and evaluate in the same region: displays result vector and executes embedded assignment (here, eval() seems to be a friend of FindRoot())


In the sheet below I tried to demonstrate how to solve a system of equations using FindRoot() as alternative to Solve(). However, I am not sure how to explain the behaviour to the students. Should we generally avoid assignment with integrated evaluation for the time being?

2018-12-12 00_06_28-SMath Studio - [Kerbformzahl Lochstab Biegung FKM.sm_].png

Kerbformzahl Lochstab Biegung FKM.sm (701kb) downloaded 12 time(s).
Martin Kraska

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Offline Davide Carpi  
#230 Posted : 12 December 2018 03:27:22(UTC)
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Originally Posted by: mkraska Go to Quoted Post
Should we generally avoid assignment with integrated evaluation for the time being?


Yes, they should be avoided. There are several known issues while using implicit assignments, I plan to remove them when I'll have the possibility to commit a major update to this plugin.

Moreover now SMath Studio supports multiple assignments by matrices on LHS, therefore it shouldn't be a big loss.

2018-12-12 01_26_35-Window.png
Best regards,

Davide

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Offline mkraska  
#231 Posted : 12 December 2018 03:41:25(UTC)
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Originally Posted by: Davide Carpi Go to Quoted Post
Originally Posted by: mkraska Go to Quoted Post
Should we generally avoid assignment with integrated evaluation for the time being?


Yes, they should be avoided. There are several known issues while using implicit assignments, I plan to remove them when I'll have the possibility to commit a major update to this plugin.

Moreover now SMath Studio supports multiple assignments by matrices on LHS, therefore it shouldn't be a big loss.



Perhaps I wasn't clear enough. My example doesn't show any problem with embedded/implicit assignment (at least nothing obvious). What I mean is if you write an assignment with := and in the same region ask for display by = . This one seems to be a problem. Maybe, the two features are related, I don't know.

If you drop integrated/implicit assignment, perhaps would be a good idea to return a set of boolean equations which can be used with at(), just like with Solve(). Then you can easily operate with multiple solutions without having to clear inbetween.
Martin Kraska

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Offline Jean Giraud  
#232 Posted : 10 February 2019 17:22:32(UTC)
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Originally Posted by: omorr Go to Quoted Post
Be my guest if you want to solve it

A similar problem problem kept the Mathsoft Collaboratory [mostly Jean]
busy for a while, solving for 22 variables. That was possible finally
from Given/Find with infinitely many trial/error constraints.
Given/Find Mathcad 8 Pro solves for 250
Given/Find Mathcad 11 solves for 400 but not of that nature
Given/Find MCD 11 solves for 399 in for loop as the next call
benefits of the previous estimates. That was done solving a DE
of variable coefficients as functions [something like Frobenius]

The Mathsoft 22 variables surely does not exist anymore in my old box
as it was "secret" about what is was. Maybe the Originator said 'thaks'
but not sure as commonly Done-Gone !
Yet, I don't completely understand the problem and its generation.

Cheers Radovan ... Jean


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Offline Jean Giraud  
#233 Posted : 10 February 2019 19:29:08(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
Be my guest if you want to solve it


Assuredly not a profitable guest !
I don't understand much in there.

Primer38-doomed.sm (40kb) downloaded 11 time(s).
Primer38-doomed_1.sm (45kb) downloaded 7 time(s).
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Offline omorr  
#234 Posted : 10 February 2019 19:45:22(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
Originally Posted by: Jean Giraud Go to Quoted Post
Be my guest if you want to solve it


Assuredly not a profitable guest !
I don't understand much in there.

Primer38-doomed.sm (40kb) downloaded 11 time(s).
Primer38-doomed_1.sm (45kb) downloaded 7 time(s).


Thank you Jeaan for your efforts, but I think we do not understand each other. This is not a fitting problem but finding roots of nonlinear system of equations

38doomed.PNG

The solution was found in Mathcad - this post - and some other software but never in SMath

Regards,
Radovan
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Offline Razonar  
#235 Posted : 10 February 2019 23:59:18(UTC)
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Originally Posted by: omorr Go to Quoted Post


Here is the same problem solved in Mathcad

Regards,
Radovan


Hi. Can you show the guess values for x and y? And k before Find too. I get a very different k value. Remember that for numerical procedures, guess values are part of the solution, not of the problem.
Thanks in advance.

Best regards.
Alvaro.
Offline omorr  
#236 Posted : 11 February 2019 11:43:53(UTC)
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Originally Posted by: Razonar Go to Quoted Post
Originally Posted by: omorr Go to Quoted Post


Here is the same problem solved in Mathcad

Regards,
Radovan


Hi. Can you show the guess values for x and y? And k before Find too. I get a very different k value. Remember that for numerical procedures, guess values are part of the solution, not of the problem.
Thanks in advance.

Best regards.
Alvaro.


Thank you Alvaro for your interest in these problems. Here is the file once more.

Primer38-doomed1.sm (32kb) downloaded 13 time(s).

This is a system of nonlinear algebraic equations. If one takes a look at the calculation here it is obvious that any gradient algorithm for solving this system will fail. Therefore, some non-gradient method might solve this (direct solving or some minimization procedure). There are some functions in the NonlinearSolvers plugin, but unfortunately, there is no update of them for a long time and many of them do not work anymore. All of these years I mentioned that we need here some well tested and robust library incorporated in SMath regarding these problems. There are no other plugins which will address these problems (AFAIK) and I am not sure that will ever be any.

Regards,
Radovan

Edited by user 11 February 2019 20:19:19(UTC)  | Reason: Not specified

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Offline Jean Giraud  
#237 Posted : 11 February 2019 22:16:54(UTC)
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Originally Posted by: omorr Go to Quoted Post
This is a system of nonlinear algebraic equations. If one takes a look at the calculation here it is obvious that any gradient algorithm for solving this system will fail. Therefore, some non-gradient method might solve this (direct solving or some minimization procedure). There are some functions in the NonlinearSolvers plugin, but unfortunately, there is no update of them for a long time and many of them do not work anymore. All of these years I mentioned that we need here some well tested and robust library incorporated in SMath regarding these problems. There are no other plugins which will address these problems (AFAIK) and I am not sure that will ever be any.

1. You seem not happy of the result by plugging [x, y] from the other software.
Did you enter enough decimals ? or that software is short of more ?
2. The Smath FindRoots is not robust in there but it can reproduce results
from your source software with more decimals that you collected.
3. Presumably the software is Matlab ?
4. In short: for a fixed Phi, you are attempting to solve pairwise [x,y]
as you scan over 'z'. Isn't true that any pairwise [x,y] will find a valid
solution or closely ? Stated otherwise: the unique non trivial pair [x,y]
is extremely sensitive to initials. That reminds me the Mathcad rootScanner
that I designed for some extremely sensitive initials. But that one tool
is only for one variable.

Cheers Radovan ... Jean

Primer38-doomed1[Solve paiWise].sm (11kb) downloaded 5 time(s).

Offline Jean Giraud  
#238 Posted : 11 February 2019 22:54:05(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
Did you enterenough decimals ?

PairWise.PNG
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Offline omorr  
#239 Posted : 11 February 2019 23:53:56(UTC)
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Hello Jean,

The solution is from Mathcad (Given/Find)

With an increased number of decimals.

decimals.PNG

Regards,
Radovan
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Offline Jean Giraud  
#240 Posted : 12 February 2019 04:45:36(UTC)
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Originally Posted by: omorr Go to Quoted Post
Hello Jean,

The solution is from Mathcad (Given/Find)
With an increased number of decimals.

That was my guess, no shame borrowing the hammer as needed.
γRK(T,x):=eval(program) ... > 4 times faster.
Cheers Radovan ... Jean

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