roots says "No real roots"

roots says "No real roots" - roots function does not work - Messages

#1 Posted: 12/28/2020 9:40:16 AM
Aleksey_here

Aleksey_here

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Tooltip is "No real roots"

Please see the full file minimal_model_9.sm (99 KiB) downloaded 35 time(s).
#2 Posted: 12/28/2020 12:18:55 PM
Jean Giraud

Jean Giraud

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Wrote

Tooltip is "No real roots"


Here, "Matrix is non-invertible, Determinant = 0"
"Units don't match" for plotting T1.
Always wise to start a project units-less, to see something.
solve, roots, Findroot work on Martin.

minimal_model_9.sm (92 KiB) downloaded 37 time(s).

#3 Posted: 12/28/2020 12:24:20 PM
Jean Giraud

Jean Giraud

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The attached is a deterministic lecture before solving.

Solve ADVANCE at(2) Read First.sm (215 KiB) downloaded 43 time(s).
#4 Posted: 12/28/2020 1:29:37 PM
Alvaro Diaz Falconi

Alvaro Diaz Falconi

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Hi. T.1(x,y) and T.2(x,y) represent surfaces. So T = [T.1,T.2] is the intersection of two surfaces. If the intersection is only a point, that's good look. But get a numerical procedure that catch it, that's square good look. Fortunately, SMath have an amazing numerical solver into a plugin. Please try this:

Clipboard01.jpg

Best regards.
Alvaro.

You need to install the plugin: https://en.smath.com/forum/yaf_postst1775_AlgLib-3-1x.aspx
#5 Posted: 12/28/2020 1:38:06 PM
Martin Kraska

Martin Kraska

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Again a version with generic units support. Note that in case of non-unique solutions the result depends on the initial guess.

minimal_model_9_Kr.sm (99 KiB) downloaded 31 time(s).
2020-12-28 17_34_43-SMath Studio - [minimal_model_9_Kr.sm_].png
Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx
#6 Posted: 12/28/2020 1:46:36 PM
Aleksey_here

Aleksey_here

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Wrote

Wrote

Tooltip is "No real roots"


Here, "Matrix is non-invertible, Determinant = 0"
"Units don't match" for plotting T1.
Always wise to start a project units-less, to see something.
solve, roots, Findroot work on Martin.

minimal_model_9.sm (92 KiB) downloaded 37 time(s).



Sorry, I cannot open your file, one plugin is incompatible with my version.

Could you explain a little what is possible to do there with that roots function ?

#7 Posted: 12/28/2020 2:03:02 PM
Aleksey_here

Aleksey_here

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I want to thank everyone who answered

I really ignored that guess values, but now, after your answers
I put the pair 0.01 and 10 for x and y in the third parameter
for the roots function and it really worked normally this time.

:-)
#8 Posted: 12/28/2020 2:52:31 PM
Jean Giraud

Jean Giraud

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Wrote

Sorry, I cannot open your file, one plugin is incompatible with my version.
Could you explain a little what is possible to do there with that roots function ?


That is really a bug version(s). Web Masters may want to plug in bug list.
"roots" works as given in my SS 6179.
I guess Martin will give more insight about that solver.
#9 Posted: 12/28/2020 8:29:57 PM
Jean Giraud

Jean Giraud

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"No real roots" may make sense considering the function.
That's your T1(x,y) stripped of units after symbolic expansion.
Do the same from the very beginning of the project, i.e: units-less.
That would help setting a convenient solve bloc.

T1(x,y).PNG
#10 Posted: 12/28/2020 10:06:52 PM
Jean Giraud

Jean Giraud

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... get inspired to construct the project units-less to see
the plot appropriately ranged. From there, easy or difficult
to solve. If you don't see the project, you have no project.
Assume your project has to pass QA. No monkey see, no monkey check.

LobeSolve.PNG
#11 Posted: 12/29/2020 1:46:48 PM
Jean Giraud

Jean Giraud

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... up to You if you want to reconciliate the project.
If you put unit 'm', that assumes all parameters are conform,
including the constant of gravity. Then, make it unit-less
in order to plot T1(x,y), T2(x,y) ... from there then, easy
to tabulate results at will and export.
Just an offer from which you may gain more from Smath.
#12 Posted: 12/30/2020 8:34:04 PM
Jean Giraud

Jean Giraud

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That's what I meant about a math project, i.e: units-less.
From T1(x,y) plot, you can decide what makes sense "solving".
As you can see, you can have 2, 4, 6 solutions
or by ranging solve correctly, only one solution.
You have to see the lobe system to appropriately range.
Check that your temperatures match, I just zapped them all
however, you had some °K, °C ... else check too.
That project is Chinese to me, but not the end objective.
Add the companion T2(x,y), follow the guidance.
At this point: monkey see, monkey can QA

minimal_model UNITS-LESS.sm (114 KiB) downloaded 28 time(s).
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