Try to use ODE solver

>
> Hello,
> I added
> https://github.com/SergeStinckwich/SciSmalltalk/wiki/Quick-start-to-ODE
>
>
> On Apr 17, 2014, at 3:03 PM, Natalia Tymchuk <[hidden email]>
> wrote:
>
> Hello, Serge.
> If you want to solve that ODE, you just need to execute
>
> (solver solve: system startState: 0 startTime: 1 endTime: 10)
>  or
> (solver solve: system startState: 0 startTime: 1 endTime: 10 stepSize: 0.1).
>
> If you want me to tell how does every step work let me know.
>
> P.S. I will add it on github wiki.
> Best regards,
> Natalia
>
>
> Четвер, 17 квітня 2014 р. 11:43:36 UTC+3 користувач Serge Stinckwich
> написав:
>>
>> Dear Natalia,
>>
>> I try to use ODE from SciSmalltalk because I want to replace our adhoc
>> RungeKutta code that we use in one my research project called Kendrick
>> about epidemiological modeling:
>> https://github.com/UMMISCO/Kendrick
>>
>> Basically diseases are modelled as a system of differential ODEs.
>>
>> Before doing that, I would like to do something simpler but I'm a bit
>> stucked at the moment :-)
>> For example, I try to mimic the 1D ODE example of odeint here :
>> http://headmyshoulder.github.io/odeint-v2/examples.html
>>
>> |dt system stepper solver|
>> dt := 0.1.
>> system := ExplicitSystem block: [:x :t | 3.0/(2.0*t*t) + x/(2.0*t)].
>> stepper := RungeKuttaStepper onSystem: system.
>> solver := (ExplicitSolver new) stepper: stepper; system: system; dt: dt.
>>
>> How do you solve the ODE ?
>>
>> Any hints ?
>>
>> Regards,
>> --
>> Serge Stinckwich
>> UCBN & UMI UMMISCO 209 (IRD/UPMC)
>> Every DSL ends up being Smalltalk
>> http://www.doesnotunderstand.org/
>
>
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> Ok I made some progress.
> I'm able to solve a simple 1D ODE :
>
> ================================================
> |dt system stepper solver state values diagram|
> dt := 0.01.
> system := ExplicitSystem block: [:x :t | (3.0/(2.0*t*t)) + (x/(2.0*t))].
> stepper := RungeKuttaStepper onSystem: system.
> solver := (ExplicitSolver new) stepper: stepper; system: system; dt: dt.
>
> state := 0.0.
> values := (1.0 to: 20.0 by: dt) collect:[:t |
> state := stepper doStep: state time: t stepSize: dt].
>
> diagram := GETDiagramBuilder new.
> (diagram lineDiagram)
> models: values;
> yourself.
> diagram open
>
> ================================================
>
> When I draw the result with GraphET, I obtain a line.
> Normally, the analytic result is : x(t) = sqrt(t) - 1/t
> as told here :
> http://headmyshoulder.github.io/odeint-v2/examples.html
>
> Any idea ?
>
> After that, I try to implement the Lorentz attractor :
>
> ================================================
> | solver stepper system dt sigma r b state values diag|
> sigma := 10.0.
> r := 28.
> b := 8.0/3.0.
> dt := 0.005.
> system := ExplicitSystem
> block: [:x :t | | c |
> c:= DhbVector new: 3.
> c at: 1 put: sigma * ((x at: 2) - (x at: 1)).
> c at: 2 put: r * (x at: 1) - (x at: 2) - ((x at: 1) * (x at: 3)).
> c at: 3 put: (b negated * (x at: 3) + ((x at: 1) * (x at: 2))).
> c].
> stepper := RungeKuttaStepper onSystem: system.
> solver := (ExplicitSolver new) stepper: stepper; system: system; dt: dt.
> state := #(10.0 10.0 10.0).
>
> values := (0.0 to: 3.5 by: dt) collect:[:t |
> state := stepper doStep: state time: t stepSize: dt].
> values.
> diag := GETDiagramBuilder new.
> (diag scatterplot)
> models: values;
> x: [ :v |v at:1];
> y: [ :v |v at:2];
> regularAxis;
> dotSize: 2.
> diag open.
> ================================================
>
> I'm able to view the nice butterfly figure. Look at the attached picture.
> When I try to draw with more points, for exemple : 0.0 to:10.0
> I have an error ... At the moment, I don't understand if this a
> problem with GraphET or SciSmalltalk.
>
> Regards,
>
> On Fri, Apr 18, 2014 at 9:59 AM, Serge Stinckwich
> <[hidden email]> wrote:
>> Thank you Natalia for starting a page about that. I think we should
>> continue to work on a more elaborate documentation.
>>
>> I understand how to solve an ODE, but now I would like to plot the
>> result between 1 and 10 for example.
>> How I could do that ?
>>
>> What represent the result of the solver ?
>>
>> Regards,
>>
>> On Thu, Apr 17, 2014 at 8:53 PM, Natalia Tymchuk
>> <[hidden email]> wrote:
>>>
>>> Hello,
>>> I added
>>> https://github.com/SergeStinckwich/SciSmalltalk/wiki/Quick-start-to-ODE
>>>
>>>
>>> On Apr 17, 2014, at 3:03 PM, Natalia Tymchuk <[hidden email]>
>>> wrote:
>>>
>>> Hello, Serge.
>>> If you want to solve that ODE, you just need to execute
>>>
>>> (solver solve: system startState: 0 startTime: 1 endTime: 10)
>>>  or
>>> (solver solve: system startState: 0 startTime: 1 endTime: 10 stepSize: 0.1).
>>>
>>> If you want me to tell how does every step work let me know.
>>>
>>> P.S. I will add it on github wiki.
>>> Best regards,
>>> Natalia
>>>
>>>
>>> Четвер, 17 квітня 2014 р. 11:43:36 UTC+3 користувач Serge Stinckwich
>>> написав:
>>>>
>>>> Dear Natalia,
>>>>
>>>> I try to use ODE from SciSmalltalk because I want to replace our adhoc
>>>> RungeKutta code that we use in one my research project called Kendrick
>>>> about epidemiological modeling:
>>>> https://github.com/UMMISCO/Kendrick
>>>>
>>>> Basically diseases are modelled as a system of differential ODEs.
>>>>
>>>> Before doing that, I would like to do something simpler but I'm a bit
>>>> stucked at the moment :-)
>>>> For example, I try to mimic the 1D ODE example of odeint here :
>>>> http://headmyshoulder.github.io/odeint-v2/examples.html
>>>>
>>>> |dt system stepper solver|
>>>> dt := 0.1.
>>>> system := ExplicitSystem block: [:x :t | 3.0/(2.0*t*t) + x/(2.0*t)].
>>>> stepper := RungeKuttaStepper onSystem: system.
>>>> solver := (ExplicitSolver new) stepper: stepper; system: system; dt: dt.
>>>>
>>>> How do you solve the ODE ?
>>>>
>>>> Any hints ?
>>>>
>>>> Regards,
>>>> --
>>>> Serge Stinckwich
>>>> UCBN & UMI UMMISCO 209 (IRD/UPMC)
>>>> Every DSL ends up being Smalltalk
>>>> http://www.doesnotunderstand.org/
>>>
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>> "SciSmalltalk" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>> email to [hidden email].
>>> For more options, visit https://groups.google.com/d/optout.
>>>
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups
>>> "SciSmalltalk" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an
>>> email to [hidden email].
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>>
>> --
>> Serge Stinckwich
>> UCBN & UMI UMMISCO 209 (IRD/UPMC)
>> Every DSL ends up being Smalltalk
>> http://www.doesnotunderstand.org/
>
>
>
> --
> Serge Stinckwich
> UCBN & UMI UMMISCO 209 (IRD/UPMC)
> Every DSL ends up being Smalltalk
> http://www.doesnotunderstand.org/