compare 1D array with rows of 2D matrix

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Muhammad Sohail Abid 2018-9-25

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评论： Muhammad Sohail Abid 2018-9-28

how to compare entries of 1D array with rows of 2D matrix. entries of 1D array are the row number of 2D matrix. after comparing we write the corresponding column value of that row and if the row number gets repeat in 1D array then we move to next column value of same row and it goes on.I need help with code

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Answer 1

KSSV 2018-9-25

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Read about ismember

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KSSV 2018-9-25

logical indexing is powerful and very fast...o get the position/ index use find.

Muhammad Sohail Abid 2018-9-28

在 MATLAB Online 中打开

Sir I have used trying index and ismember, but not able to find any of the result can you please make a code for relating image pixel values with points on table. here is the code which I made

here is code
disp('y^2 = x^3 + 5376x + 2438 mod 123457')
a=0:123456;
left_side = mod(a.^2,123457);
right_side = mod(a.^3+5376*a+2438,123457);
points = [];
for i = 1:length(right_side)
I = find(left_side == right_side(i));
for j=1:length(I)
points = [points;a(i),a(I(j))];
end
end
plot(points(:,1),points(:,2),'ro')
set(gca,'XTick',0:1:123456)
set(gca,'YTick',0:1:123456)
grid on;
pad_needed = 256 - (mod(size(points,1) - 1, 256) + 1);
if pad_needed > 0
points(end+pad_needed,:) = 0;
end
T = points;
Z = reshape(T,256,482,2);
img=rgb2gray(imread('lena.jpg'));
V=img(:);
V=V';