finding minimum value with index

Hi

I have a matrix 3 dimensions. i,j,t(time). I try to find minimum for part of matrix when 85<j<170; 50<i<80 for each time step. In other words, the minimum of for all(one page).Also, I need in the location which i,j(index).

How can I do it?

Answer 1

[Amith]

As per my understanding you wanted to know how you can find the minimum value and their corresponding indices for a submatrix in the range for i=(86,169) and j=(51,79) for every time step. Below is the code provided for performing the same.

%defined the timesize as 10.
timesize = 10;

%generated a matrix of random numbers.
matrix = randn(80,170,timesize);

index_x = zeros(1,timesize);
index_y = zeros(1,timesize);
minvalues = zeros(1,timesize);


for time = 1:timesize
    
    %takes a submatrix for that particular time step
    A = matrix(51:79, 86:169, time);
    
    %finds the minimum value and index but as linear indices.
    [minimum_values, index] = min(A, [], [1 2],'linear');
    
    %storing minimum values
    minvalues(time) = minimum_values;
    
    %converts linear indices into subscripts (i.e into actual i,j indices)
    [row, col] = ind2sub(size(A), index);
    
    %adding the starting index as we have taken submatrix and have done
    %operations on that
    
    index_x(time) = row+51-1;
    index_y(time) = col+86-1;
end


disp(index_x) %gives the minimum values x index
disp(index_y) %gives the minimum values y index
disp(minvalues) %provides the minimum values for the each time instance