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Offline johnpan  
#1 Posted : 11 May 2022 06:02:05(UTC)
johnpan


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Hi, Guys:

I'm using FindRoot for SOE solution,but something make me confusion. for example:

smath soe q1.jpg

the same SOE with different variables, different result, and the second is wrong.

I think maybe I have something wrong. please help me, how to use the FindRoot?

Thanks a lot!

John

attach the file
soe.sm (7kb) downloaded 6 time(s).
Offline Razonar  
#2 Posted : 11 May 2022 06:24:23(UTC)
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Hi. You must to sort the variables in the same order than Unknowns.

Clipboard02.jpg

Best regards.
Alvaro
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on 11/05/2022(UTC)
Offline johnpan  
#3 Posted : 11 May 2022 07:49:05(UTC)
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Originally Posted by: Razonar Go to Quoted Post
Hi. You must to sort the variables in the same order than Unknowns.

Clipboard02.jpg

Best regards.
Alvaro


Hi, is there any rules for the order?

smath soe q2.jpg

Thanks alot
John
Offline Razonar  
#4 Posted : 11 May 2022 09:32:40(UTC)
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Hi. You can't redefine Unknowns. Well, you can, but isn't the best idea. Unknowns is a function in the same plugin than FindRoots, SpecialSolvers. I don't know the internals of the plugin. My guess that the general rule is sort the variable names in lexical order, but if the name has unicode characters or some unusual ASCII character, it is best to make sure of the order to follow by evaluating Unknows(eq).

Best regards.
Alvaro.
Offline johnpan  
#5 Posted : 11 May 2022 11:30:29(UTC)
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okay, I got it. but a new question, why I can't got the result as your picture?

smath soe q3.jpg

would you mind post the sample sm file ?

Thanks a lot!
John

Edited by user 11 May 2022 11:33:01(UTC)  | Reason: Not specified

Offline Razonar  
#6 Posted : 11 May 2022 12:22:01(UTC)
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Originally Posted by: johnpan Go to Quoted Post
okay, I got it. but a new question, why I can't got the result as your picture?


SMath have two "=": Numerical and Symbolical. With numerical evaluation you can only obtain numerical values, that is, without undefined variables. Rigth click to change it to symbolic equals, or use Ctrl+period instead "=", or click symbolic evaluation in the right panel.

Originally Posted by: johnpan Go to Quoted Post

would you mind post the sample sm file ?


Sorry, I forgot to post it, and right now can't.

Best regards.
Alvaro.

Offline johnpan  
#7 Posted : 11 May 2022 12:36:21(UTC)
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Clap
thank you!

I got it.

Thanks a lot!
John
Offline Jean Giraud  
#8 Posted : 11 May 2022 14:31:04(UTC)
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OBSERVE ... so much from so little

Solve Algebraic, NON-Algebraic Read first.sm (70kb) downloaded 6 time(s).
Offline Jean Giraud  
#9 Posted : 11 May 2022 14:56:57(UTC)
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This multi solve companion is 3 x 3
Make it 2 x 2 ... n x n ... as per your project.

Solve Algebraic, MULTISOLVE Companions.sm (18kb) downloaded 8 time(s).
Offline overlord  
#10 Posted : 11 May 2022 21:32:03(UTC)
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You can automate assigning guesses to unknowns.
By this way, you won't care order of them.

Regards

findroot_auto.sm (5kb) downloaded 16 time(s).

2022-05-11_21-29.png
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on 11/05/2022(UTC),  on 12/05/2022(UTC)
Offline Jean Giraud  
#11 Posted : 12 May 2022 14:44:12(UTC)
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Originally Posted by: Jean Giraud Go to Quoted Post
For your example, make it algo style for local infinite use.
Observe ... sols:=U^-1*V is universal outside of Smath Plugin(s)

... your question about order of vars
solutions are by convention in descending order of the pair wise u, v
no matter the names you give.
I can't explain the decimals difference between MCD 11/Smath.
There are other constants that can't be found exactly ...
Pitot constant, Goat radius constant ...
That remark applies to any solvers [Smath and wrt any CAS]
The U^1*V is the core component of the Cholesky solver
as applied to fitting model function to a data set.
In that case, best fit is obtained by iterating the Genfit.
Chers ... Jean.

Solve Algo.PNG
Offline Jean Giraud  
#12 Posted : 12 May 2022 15:46:19(UTC)
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... here, you can push the cork in the bottle to accommodate irrational pi.
as well ignore epsilon.

Solve f(x,y,z).PNG
Offline Jean Giraud  
#13 Posted : 12 May 2022 16:11:31(UTC)
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... as it looks, the max I could push the cork in the bottle
y≡0.279339266990994 ... sanity f(x,y,z)=-0.000000000001344
Confirms impossible exactly solving irrational numbers.
Offline overlord  
#14 Posted : 13 May 2022 00:51:29(UTC)
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Long word short, there is an order for vars.
You can either avoid it manually or automatically.
It is up to users choice which suits them most.
Either one has advantages over other.

Regards
Offline johnpan  
#15 Posted : 15 May 2022 14:04:08(UTC)
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Thank you all so much!

a nice forum Good
Offline churichuro  
#16 Posted : 15 May 2022 17:21:14(UTC)
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I never thought the time would come when I would become an expert at ignoring specific comments on a forum...thanks Jean! Dry
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on 16/05/2022(UTC)
Offline Jean Giraud  
#17 Posted : 15 May 2022 19:20:51(UTC)
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Originally Posted by: johnpan Go to Quoted Post
Thank you all so much !

Solving is very important in Engineering Projects.
Reserve ... solve, roots, FindRoots and more to specific applications
Solving a square matrix goes via the conventional solver, no flaw.
This didactic document has been refreshed.
Cheers ... Jean.

Solve Algebraic, MULTISOLVE DIDACTIC.sm (22kb) downloaded 12 time(s).

Offline Jean Giraud  
#18 Posted : 15 May 2022 21:26:39(UTC)
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Originally Posted by: churichuro Go to Quoted Post
I never thought the time would come when I would become an expert at ignoring specific comments on a forum.
...Thanks Jean!

Many of the advanced Smath documents are join venture.
Adapted/exemplified from various sources.
Download: Samples, Utilities Most used_3.
If something is not clear, please don't hesitate.
You have more, please offer.
Take care Amigo ... Jean.

Offline overlord  
#19 Posted : 15 May 2022 21:34:46(UTC)
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No churichruo, dont.
If you will post same worksheets 600 times, (satire here)
and then you will tease how less another one contributed,
and how your post statistic is 18.3% of entire forum,
Please don't.

You will just make a fool of yourself.
thanks 1 user thanked overlord for this useful post.
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Offline Jean Giraud  
#20 Posted : 16 May 2022 16:35:46(UTC)
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Originally Posted by: overlord Go to Quoted Post
No churichruo, dont.
...
You will just make a fool of yourself.

Do you mean churichruo will make a fool of himself
from reputed contributors in this document:
Mathsoft, Robert Adair, Carlos, Martin, Viacheslav, Romberg,
Riemann FD, Hermite Polyline, Legendre, Gram_Schmidt,
Guiseppe Borzi [simplex], Mathsoft Collaboratory Convolution ...
I will add Fresnel [Clothoid].
churichruo wrote Tanks Jean
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