Ode solvers implementation

Ode solvers implementation - Mensajes

#1 Publicado: 29/11/2018 19:09:04
Alvaro

Alvaro

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Hi. I can't reproduce this in SMath.

Clipboard01.gif

Archivo no encontrado.Archivo no encontrado.

Best regards.
Alvaro.
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Вячеслав Мезенцев 30/11/2018 3:25:00, Radovan Omorjan 30/11/2018 5:06:00
#2 Publicado: 29/11/2018 23:48:00
Jean Giraud

Jean Giraud

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Wrote

I can't reproduce this in SMath.



1/1 in Smath 6179, proof: the snippet.

Cheers Alvaro

IntegrateODE.PNG

Integrate with ode solver.sm (29,07 KiB) descargado 1316 vez(es).
#3 Publicado: 29/11/2018 23:59:54
Jean Giraud

Jean Giraud

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Wrote

I can't reproduce this in SMath.


You may not be able to implement the Mathcad bloc Given/ODEsolve.
ODEsolve is based on linterp. That is the first point.
The other point is that in Mathcad "linterp(x)" is a scalar function.
In Smath: ainterp, cinterp, linterp are simply interpolation fncts
They are not scalar functions. How does it reflects in ODEsolve ?
In Smath, ln(x), exp(x), ... are scalar from source code.
I tried to make cinterp scalar like in Mathcad, not to avail.

Please, persist on such a beautiful idea.

#4 Publicado: 30/11/2018 1:16:48
Jean Giraud

Jean Giraud

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Wrote

I tried to make cinterp scalar like in Mathcad, not to avail.


This document was essentially designed to plot scalar the derivative on canvas,
as well as get a discrete export. Also included: the scalar quadratic.

Cheers ... Jean

Spline Deriv Infinitesimal.sm (70,87 KiB) descargado 1330 vez(es).


#5 Publicado: 30/11/2018 2:31:22
Alvaro

Alvaro

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Wrote


You may not be able to implement the Mathcad bloc Given/ODEsolve.



Hi Jean. Actually not, just the solver, without the given.
I found how to call the odesolver, with D(x,y)=[f(x)].
This method is much more faster than the direct integration.
But remains the ln(0) error, which seems to be a bug in the odesolvers, because zero isn't in the domain range.

Clipboard01.gif

Integrate with ode solver.sm (10,17 KiB) descargado 1257 vez(es).

Best regards.
Alvaro.
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Radovan Omorjan 30/11/2018 5:10:00
#6 Publicado: 30/11/2018 3:35:52
Вячеслав Мезенцев

Вячеслав Мезенцев

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The zero point is used to determine the dimension of the vector D(t,x) at runtime (D(0, x0)). The size of the system must be determined for the further operation of the numerical algorithm. It seems that it would be correct to substitute the beginning of the interval. I will try to change this. Also, if possible, I will support the one-dimensional case.
Russia ☭ forever, Viacheslav N. Mezentsev
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sergio 30/11/2018 5:43:00, frapuano 30/11/2018 5:37:00, Alvaro 30/11/2018 4:53:00, Radovan Omorjan 30/11/2018 5:06:00
#7 Publicado: 30/11/2018 5:01:06
Alvaro

Alvaro

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Thanks Viacheslav. It's amazing the effort that you and the others plugins developers put in enhance SMath, with very spectacular results.
Best regards.
Alvaro.
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#8 Publicado: 30/11/2018 12:29:42
Jean Giraud

Jean Giraud

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Wrote

Hi Jean. Actually not, just the solver, without the given.
I found how to call the odesolver, with D(x,y)=[f(x)].
This method is much more faster than the direct integration.
But remains the ln(0) error, which seems to be a bug in the odesolvers, because zero isn't in the domain range.



Buenos dias Alvaro !

ln(0) was introduced in Mathcad 11 soon after release via update [from recollection]
There is more in the attached, specially wrt parametric D(,,,).
Jean

ODEsolve.PNG

ODE 0_Model General.sm (29,47 KiB) descargado 1291 vez(es).


#9 Publicado: 30/11/2018 12:34:54
Jean Giraud

Jean Giraud

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...

ODEsolve.PNG
#10 Publicado: 30/11/2018 15:36:38
Jean Giraud

Jean Giraud

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... refreshed version wrt explore all solvers.

ODE 0_Model General.sm (38,44 KiB) descargado 1253 vez(es).
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Alvaro 30/11/2018 15:54:00, frapuano 30/11/2018 17:58:00, Davide Carpi 3/12/2018 21:18:00
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