How i select a part or section of a matrix ?

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Louis-Philippe Talbot
评论： Image Analyst 2022-7-26
So I want to compare the matlab function inv(A) (to have a matrix inverse of A) with the way we suppose to do at hand the function is : >>> rref([A eye(size(A))]) So example : I got a something like (but freaking bigger (9*18))
* [ 1 0 a b [a b
* 0 1 c d ] and I just want to keep the c d]
[1, 0, a, b; 0, 1, c, d] >>> [a, b; c, d]
How I supposed to do It look like it super simple but now I got no idea how to do. Thank

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回答（1 个）

Image Analyst
Image Analyst 2014-3-4
out = m(:,3:4); % Extract columns 3 and 4 only into a new 2D array.
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Muhammad Taha Manzoor
Muhammad Taha Manzoor 2022-7-25
Hello Image Analyst,
I have a big matrix of some solar flux measurements. I am able to plot the flux map using imagesec but my I am intrested in the flux values which fall in 50 mm dia of circle. I can create a circluar ROI on the image but how do I extract the data within that circle? I mean I have the data stroed in a matrix I just need to crop out the relavent values in the 50 mm dia and then take an avergae of those values
Image Analyst
Image Analyst 2022-7-26
@Muhammad Taha Manzoor make your binary image mask of the circle, like with poly2mask or however, then do
meanIntensity = mean(fluxImage(mask))

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