# force input in ode

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Bhanu Pratap Akherya 2021 年 8 月 24 日

i have a set of values for the force term "F" (in the equation my"+cy'+ky=F) saved in an excel file which i have recalled using:
My main code looks something like:
y0=initial conditions
[tsol ysol]=ode15s('beam_function',[1:dt:T],y0);
plot(tsol,ysol);
whereas, my function code looks something like:
function [dy]=beam_function(t,y)
dy=[y(1:u-1);
inv(M)*(F-K*y(u:end)-C*y(1:u-1))]
The problem is that i want to recall each value of F at different time steps but i dont know how to do that, can anyone guide me?
Note: F here is not time dependent rather it has been taken from results obtained from a simulation software. Then what should be my approach?

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### 採用された回答

darova 2021 年 8 月 24 日
for i = 1:length(F)
[t,y] = ode45(@(t,y)beam_function(t,y,F(i)),...)
end
function dy = beam_funciton(t,y,F)
##### 6 件のコメント表示非表示 5 件の古いコメント
darova 2021 年 8 月 29 日
Maybe you need another ode function
function [dy]=beam_function(t,y)
n = numel(y);
dy(n/2) = y(end);
dy(end) = inv(M)*(F-K*y(end)-C*y(end));
And solve it separately

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