find(V,1) returns an index that doesn't match with the plot

Question

Abdallah 2022-8-5

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评论： Abdallah 2022-8-5

>> find(SL_B_Optml,1)
ans =
381
>> plot (linspace(1,1441-(T_B+1)+1,1441),SL_B_Optml);
>> hold on
>> plot([381 381],[0 1.4],'LineWidth',1)

First of all, the find funciton tells us that my SL_B_Optml array reaches a non-zero value for the first time at the x=381.

The plots written above give this:

We can clearly see that SL_B_Optml array reaches the first non-zero value at x=358.3.

I don't understand what's happening here.

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Torsten 2022-8-5

在 MATLAB Online 中打开

Is SL_B_Optml a vector, a matrix ?

What do you get when you type

size(SL_B_Optml)

before the "find" command ?

Abdallah 2022-8-5

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@Torsten

>> size(SL_B_Optml) 
ans =
1        1441

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Answer 1

Cris LaPierre 2022-8-5

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Find tells you the index value of the elements of SL_B_Optml that meet your criteria. It therefore will be an integer value. However, that is different than an x-value of 381. Here, your x values are linspace(1,1441-(T_B+1)+1,1441).

You should therefore highlight your point doing something like this:

x=linspace(1,1441-(T_B+1)+1,1441);
plot([x(381) x(381)],[0 1.4],'LineWidth',1)

We don't have your values, so I can't check if there is anything else wrong.

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Abdallah 2022-8-5

Find tells you the index value of the elements of SL_B_Optml that meet your criteria. It therefore will be an integer value. However, that is different than an x-value of 381.

This.You're right, sir, I get it now, thanks.

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