How can I find an specific value inside an array without using the find function?

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Pipe
Pipe 2022-8-28
评论： Walter Roberson 2022-8-28
I need to store the index when w>=10 in an array without using the find function. So for example in my code w=10 at t1 8. Is there any way to do that without using the find function?
array=zeros(2,2);
t=0:20;
i=2;
dwdt = @(t,w)(-2.*w+5.05.*w.^0.6);
[t,w] = ode45(dwdt,t,0.5);
%w=10 @ t= 8
index= find(w>=10);%dont use find function
array(i)= index(1);
  1 个评论
Walter Roberson
Walter Roberson 2022-8-28
What is the reason to avoid find()? There are ways to get indices in a vectorized way without using find() but they are not especially efficient for large matrices.

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Voss
Voss 2022-8-28
编辑：Voss 2022-8-28
Ran in:
You can use the max function with second output argument, applied to the logical array w>=10, in order to return the first index where w>=10.
array=zeros(2,2);
t=0:20;
i=2;
dwdt = @(t,w)(-2.*w+5.05.*w.^0.6);
[t,w] = ode45(dwdt,t,0.5);
%w=10 @ t= 8
[~,index] = max(w>=10);
disp(index)
8
array(i)= index(1);

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