How to create a loop to run my ODE for two sets of data and then store each data set in two cell arrays.

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Jacob 2023-3-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1928670-how-to-create-a-loop-to-run-my-ode-for-two-sets-of-data-and-then-store-each-data-set-in-two-cell-arr

评论： Jan 2023-3-15

采纳的回答： Jan

function [dAsdt]=rates(tspan, y)

% Rate constants

K1 = 0.4526;

K2 = 0.3958

K3 = 0.3523

%ODE for each spicies in reactor

dA1dt = -K1*y(1)*y(2) -K2*y(1)*y(4) -K3*y(1)*y(5);

dA2dt = -K1*y(1)*y(2);

dA3dt = K1*y(1)*y(2) +K2*y(1)*y(4) +K3*y(1)*y(5);

dA4dt = K1*y(1)*y(2) -K2*y(1)*y(4);

dA5dt = K2*y(1)*y(4) -K3*y(1)*y(5);

dA6dt = K3*y(1)*y(5);

%combine all ODEs into one matrix

dAsdt = [dA1dt; dA2dt; dA3dt; dA4dt; dA5dt; dA6dt]

the initial script with the ODEs called rates.

Y0 = [3 1 0 0 0]

Y1 = [4 2 0 0 0]

tspan = [0:0.1:5];

[tout,yout]=ode45('rates',tspan,y0);

I want to Run this part for both Y0 and then Y1 and store each set of values but don't know how.

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Answer 1

Jan 2023-3-14

I do not see the problem:

Y0 = [3 1 0 0 0] 
Y1 = [4 2 0 0 0] 
tspan = 0:0.1:5;
[tout{1}, yout{1}] = ode45(@rates, tspan, Y0);
[tout{2}, yout{2}] = ode45(@rates, tspan, Y1);

Notes:

0:0.1:5 is a vector already. [ ] is Matlab's operator for a concatenation. In [0:0.1:5] you concate the vector 0:0.1:5 with nothing, so this is a (tiny) waste of time.
Providing the function to be integrated as CHAR vector is outdated for over 20 years now. Use "modern" function handles instead.

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Jacob 2023-3-14

I'm confused as what you mean by providing a function as a CHAR vector as I'm very new to Matlab.

Jan 2023-3-15

ode45('rates',tspan,y0)
%     ^^^^^^^   function is provided as CHAR, outdated sind R6.5 (2002)
ode45(@rates, tspan, Y0)
%     ^^^^^^   function is provided as function handle

Where did you got the example with using a CHAR vector from? Prefer to learn Matlab from modern sources.

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