how to plot multiple decaying exponentials in one plot.

Question

Romio 2019-5-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463105-how-to-plot-multiple-decaying-exponentials-in-one-plot

评论： Alex Mcaulley 2019-5-20

I would like to plot multiple decaying exponentials with different parameters (time, decay, peak). I was able to create this code to plot only one decaying exp. at t=20

clc,clear,close all
time = [20];
peak = [5];
decay = [2];
t = 1:100;
X = zeros(length(t),1);
for j = 1:length(t)
    for i = 1:length(time)
        if t(j) > time(i)
            X(j) = peak(i)*exp(-(t(j)-time(i))/decay(i));
        end
    end    
end
plot(t,X)

now say I have arrays of parameters like this

time = [20 50 80];
peak = [5 3 2];
decay = [2 4 6];

and I want to plot three consecutive decaying exponentials using each element of these parameters. Any thoughts on how to go about it?

Thanks,

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Answer 1

Alex Mcaulley 2019-5-20

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463105-how-to-plot-multiple-decaying-exponentials-in-one-plot#answer_375863

在 MATLAB Online 中打开

Here two options:

time = [20 50 80];
peak = [5 3 2];
decay = [2 4 6];
% Symbolic toolbox needed
figure
syms t
X = peak.*exp(-(t-time)./decay);
fplot(X,[1,100])
%Anonymous functions
figure
t = 1:100;
X = @(t) peak.*exp(-(t-time)./decay);
plot(t,cell2mat(arrayfun(X,1:100,'UniformOutput',false)'))

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Romio 2019-5-20

Thanks. But they do not correspond to the parameters (e.g. they should be at 20 50 80 with the spcified amplitudes/decay). Also I need them in a loop fasion so that I can use them as an input to dfferent program.

Alex Mcaulley 2019-5-20

在 MATLAB Online 中打开

Why do you want to do it with loops? It is inefficient, but you can do it easily adding another loop (from 1 to size(time)).

By the way, following my previous code, to shift the exponentials to the desired position:

time = [20 50 80];
peak = [5 3 2];
decay = [2 4 6];
t = cell2mat(arrayfun(@linspace,time,100*ones(size(time)),'UniformOutput',false)');
X = @(t) peak.*exp(-(t)./decay);
plot(t',cell2mat(arrayfun(X,linspace(0,100),'UniformOutput',false)'))