Try to use ODE solver
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Try to use ODE solver
 
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Re: Try to use ODE solver
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Re: Try to use ODE solver
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Re: Try to use ODE solver
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Re: Try to use ODE solver
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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/ -- 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. |
Screen Shot 2014-04-18 at 12.34.15.png (133K)
Re: Try to use ODE solver
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