Finding maximum of rows, colums, overall in matrix

I am completely stumped on a problem here. I've been playing around with it for hours now to no avail. I have to create a script that will prompt the user to enter their desired matrix dimensions. Then perform each of the following using loops (Not using that ‘max’ built in function’ but you may use if statements if necessary): · Find the maximum value in each column. · Find the maximum value in each row. · Find the maximum value in the entire matrix.

[Azzi Abdelmalek]

What have you tried so far with your homework?

Answer 1

[Image Analyst]

Hours? Wow. Hint:

[rows, columns] = size(yourMatrix);
maxOfRows = -inf * ones(1, rows);
maxOfColumns - .....
for col = 1 : columns
  for row = 1 : rows
    if .... > ...
    end
  end
end

I hope that's enough to get you started. See if you can fill it out from there.

[Chris]

I just don't understand how the loop works. What would I put for the if statement? To start my code I have my input statements creating a random matrix from 0-100.

num_rows = input('Enter the number of rows:'); 
num_cols = input('Enter the number of columns:'); 
mat = randi([0,100],num_rows,num_cols) 
[rows, columns] = size(mat); 
maxOfRows = -inf*ones(1,rows) 
maxOfCols = -inf*ones(1,columns)

I'm thinking the if statement would go.

if mat(rows,columns) > 0

The script also has to print the values of the maximum of each row, column, and the overall. I know I can do the entire script with one nested for loop and if statement.

[Image Analyst]

You want to see if your matrix is greater than the max for the row and column the current element is in, so the first part is right, but you don't want to compare it to zero, you want to compare it to the latest max value for that row and column, don't you? And if it is, you need to store that value into the max arrays. And to check the current location, you check mat(row, col) because row and col are the indexes which change as you move through the array. rows and columns don't change so mat(rows, columns) refers to the very last (lower right) corner of the matrix and never changes.

if mat(row, col) > maxOfRows(row)
  % Save this value in our max matrix.
  maxOfRows(row) = mat(row, col);
end
if mat(row, col) > maxOfCols(col)
  maxOfCols(col).........

Try to finish that.

[Cedric]

Catherine, start a new thread, reference this one if necessary, and give an example. The more specific you are, the more likely you'll get an answer.