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Matlab max and min of a matrix

  1. Oct 1, 2011 #1
    Hi, I want to find the maximum and minimum values of a column in a matrix.
    I have a 4 column, 100 row matrix and need the minimum and maximum value in the 4th column. I need this to be extracted along with the other values of that row. Can anyone help?
  2. jcsd
  3. Oct 2, 2011 #2
    Try "help max" and "help min."

    [Y,I] = MAX(X,[],DIM)

    Y is the max value of X taken along the dim- dimension at the index I.

    For your case in particular, let X be your matrix. To tell matlab to look at the 4th column only you would write X(:,4) which says "X at all rows and the 4th column." Then
    [Y,I] = max(X(:,4))
    will give you the maximum element Y and the index I in which that occurs. Now the row that corresponds to that maximum is the I-th row. To get the I-th row, write X(I,:) which say "X at the I-th row and all columns"

    Hope that helps.
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