How to apply NonNegativity constraint in ODE solver when defining ode as a structure

Question

Sayeeda Syed 2024-8-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2147519-how-to-apply-nonnegativity-constraint-in-ode-solver-when-defining-ode-as-a-structure

评论： Sayeeda Syed 2024-9-2

I am trying to perform a local sensitivity analysis on the parameters of my model using odeSensitivity. Taking help from this page https://in.mathworks.com/help/matlab/ref/odesensitivity.html. but the problem is that when I used to code the ode simply I put nonnegativity under options, but now i am not able to do that. I tried taking F.NonNegative=ones(1,n_parameters) but that doesnt seem to work.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Steven Lord 2024-8-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2147519-how-to-apply-nonnegativity-constraint-in-ode-solver-when-defining-ode-as-a-structure#answer_1504324

The relevant property of the ode object to specify that some of the variables must be non-negative is NonNegativeVariables. After you've set up that property, create the odeSensitivity object and set it to the ode object's Sensitivity property.

7 个评论
显示 5更早的评论隐藏 5更早的评论

Steven Lord 2024-8-26

在 MATLAB Online 中打开

NonNegativeVariables is a property of the ode object, not the odeSensitivity object. Using the example from the odeSensitivity documentation page with one addition:

p = [0.05 1.5];

F = ode(ODEFcn=@(t,y,p) [p(1)*y(1)-y(2); -p(2)*y(2)], ...

InitialValue=[2 3], ...

Parameters=p, ...

Sensitivity=odeSensitivity, ...

NonNegativeVariables = 2) % constrain the 2nd variable to be non-negative

F =

ode with properties: Problem definition ODEFcn: @(t,y,p)[p(1)*y(1)-y(2);-p(2)*y(2)] Parameters: [0.0500 1.5000] InitialTime: 0 InitialValue: [2 3] NonNegativeVariables: 2 Sensitivity: [1x1 odeSensitivity] Solver properties AbsoluteTolerance: 1.0000e-06 RelativeTolerance: 1.0000e-03 Solver: auto SelectedSolver: cvodesNonstiff Show all properties

Note that F has a Sensitivity property and a NonNegativeVariables property in its display. The NonNegativeVariables property probably won't do much (based on the picture in the example) as it looks like y(2) never becomes negative, but you can specify it.

S = solve(F,0,5)
S = 
  ODEResults with properties:

           Time: [0 2.9540e-09 2.9543e-05 2.2466e-04 4.1978e-04 0.0024 0.0139 0.0255 0.0484 0.0713 0.1363 0.2014 0.2992 0.3970 0.4948 0.6661 0.8373 1.0085 1.1798 ... ] (1x34 double)
       Solution: [2x34 double]
    Sensitivity: [2x2x34 double]

As long as you can define your ODE function that accepts t, y, and p inputs and returns the right-hand side of your system of differential equations this approach should work.

Steven Lord 2024-9-1

Please send the code you're using to solve the system to Technical Support directly using this link. That way the development staff can investigate to determine if there is a bug in the sensitivity analysis code or if there's a modifiation required in your code.

Sayeeda Syed 2024-9-2

I have sent the code through the link, I will be waiting for a reply, thank you very much

请先登录，再进行评论。

How to apply NonNegativity constraint in ODE solver when defining ode as a structure

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

回答（1 个）

7 个评论
显示 5更早的评论隐藏 5更早的评论

另请参阅

类别

标签

产品

版本

Community Treasure Hunt

How to apply NonNegativity constraint in ODE solver when defining ode as a structure

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

回答（1 个）

7 个评论 显示 5更早的评论隐藏 5更早的评论

另请参阅

类别

标签

产品

版本

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

7 个评论
显示 5更早的评论隐藏 5更早的评论