Loop generation doubt.

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Martin Thomas
Martin Thomas 2020-8-22
评论： the cyclist 2020-8-23
Hi,
I need to create a loop. I have to do a numerical analysis of thousands of data points.
My equation is,
E=A*cos(k-(w*t))
I have A,k and w three of them have same length 1x10. In the case of t which i have 1x50.
what i have to do is i need to take the first value of A,k and w and vary t (means run with range of values) . I need to do the same processs for the rest of the rows of A,k and w and vary t.
To be more precise.
A k w T
1 1 1 1
2 2 2 2
3 3 3 3
4 4 4 4
N N N 5
6
N
the equation will be
First calculation need to be
E=1*cos(1-(1*(1....N)))
second
E=2*cos(2-(2*(1....N)))
.......
continue upto length of A,k,w

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采纳的回答

the cyclist
the cyclist 2020-8-22
% DO NOT USE THESE. USE YOUR DATA. THESE ARE FOR AN EXAMPLE ONLY
T = rand(160547,1);
A = rand(44880,1);
k = rand(size(A));
w = rand(size(A));
%%%%%% Only use the code below %%%%%
% Preallocate memory for E
E = zeros(1,160547);
% Calculate E
for ii = 1:size(E2,2)
E(ii) = sum(A.*cos(k-(w.*T(ii))));
end
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Martin Thomas
Martin Thomas 2020-8-23
hey one more doubt, i think you know the fft, in the fft amplitude plot from the above code you can see lot of peaks, moreover if i do the fft on any signal it will give me some more additional values is that possible to remove those values from that.
the cyclist
the cyclist 2020-8-23
I don't really use fft. I would open a new question, and upload an image of the plot using INSERT again, along with the code that generates it.
Try to be very clear about your exact question.

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更多回答（1 个）

the cyclist
the cyclist 2020-8-22
编辑：the cyclist 2020-8-22
You don't need to use a loop. MATLAB will do vectorized calculations.
If you have a fairly recent version of MATLAB, you can do this using implicit expansion of the vectors:
% Make up some data
A = rand(1,10);
k = rand(1,10);
w = rand(1,10);
t = rand(1,50);
% Calculate E
E = A.*cos(k-(w.*t'));
The output E will be 50x10.
Note that I took the transpose of t, and also used element-wise multiplication and not matrix multiplication. You can read about the difference here.
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Martin Thomas
Martin Thomas 2020-8-22
I have a time vector of
T=1:(1/128):1200 160547x1 double
A= fft results (amplitude) 44880x1 double
k=(same length of A) 44880x1 double
w= frequency (same lenth of A) 44880x1 double
The problem is T does not have equal length so i can't do the E. the only way i need to do is calculating first row of A,k and w with varying T will get a result same i need to be don in the second row, thrid until the end of the A,k and w value. then i wll sum it up
E = SUM(A.*cos(k-(w.*t')));
Martin Thomas
Martin Thomas 2020-8-22
So there willbe 160547x44880 or 44880x160547 matrix after summing up the values ther will be 160547x1 double matrix

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