# Holding the Previous Value of For Loop and Sum

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tinkyminky93 2022년 5월 16일
댓글: tinkyminky93 2022년 5월 18일
Hello,
I am trying to plot the values of two operations and I have two nested for loops. For every value of k, the clutter location changes and I want to calculate the conv_clutter for the new k value. Some part of the code is like that.
for k = 1:clutternumber
clutter_x = xa1(k);
clutter_y = ya1(k);
clutter_location = [clutter_x clutter_y ];
for i = 1:1:1024
target_location = ...........
conv_target = ..
conv_clutter = ..
sum = conv_target + conv_clutter;
data(i,:) = sum;
end
end
imagesc(real(abs(data)), 'XData', [range]), colormap turbo;
I cannot hold the previous value of the conv_clutter in imagesc. Can someone help me about the algorithm? It just shows me the value that comes from the k = 1 and the others are constant.

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### 채택된 답변

Jon 2022년 5월 16일
The problem is that you overwrite your value of data each time the inner loop is executed.
If you just want to plot each image and not do anything else with it, you could move your line that plots the data inside of the loop and make a new figure for each plot, so something like this:
for k = 1:clutternumber
clutter_x = xa1(k);
clutter_y = ya1(k);
clutter_location = [clutter_x clutter_y ];
for i = 1:1:1024
target_location = ...........
conv_target = ..
conv_clutter = ..
sum = conv_target + conv_clutter;
data(i,:) = sum;
end
% plot the image
figure
imagesc(real(abs(data)), 'XData', [range]), colormap turbo;
end
If you want to do more with the data, then you will need to save it, for example in an array with three dimensions, the first dimension could be the clutternumber, and the other two would provide the image, or you could make a cell array of images
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Jon 2022년 5월 18일
Sorry, I am not familiar enough with your problem domain to understand what you are saying. If you could express it more generically, explaining what mathematical operations you are performing, what your "image" is and what exactly you want saved I might be able to help further. Otherwise the general advice I would give you is that if you do not want a variable in the inner loop to keep overwriting something then you need to save it with a variable that includes some kind of index from the outer loop.
tinkyminky93 2022년 5월 18일
I solve it sir, your thoughts are right. I just want to overwrite it but the way that i use is not true. data(i,:) = data(i,:) + sum; solves my problem. I was writing like data(i,:) = convolve_rx + convolve_rx_clutter + sum;
Thank you so much.

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