Find max of matrix without using built in function.

I want to find the "max(a)" without actually using the built in "max" function.

[Roland]

I'm trying to do this with a for loop as test preparation.

[Sean de Wolski]

We won't do your homework for you. What have you tried so far.

Answer 1

[Paulo Silva]

mx=a(1);
for p=2:numel(a)
  if a(p)>mx
   mx=a(p);
  end
end

mx %the maximum value

[Roland]

How would I find the max of each column individually?

[Paulo Silva]

%code made here, not tested in matlab

mxc=zeros(1,size(a,2));

for n=1:size(a,2)

mx=a(1,n);

for p=2:size(a,1)

if a(p,n)>mx

mx=a(p,n);

end

end

mxc(n)=mx;

end

mxc %the maximum value per column

[Paulo Silva]

The code isn't optimized on purpose, like Sean said "We won't do your homework for you"

Answer 2

[Sean de Wolski]

the_max = -min(-(a(:)))

[Roland]

I need to use logical operators.

[Sean de Wolski]

the_max = a(a==-min(-(a(:))))

There!

Answer 3

[Adrien Leygue]

The following code will extract the minimum over each column. No loop no max no min and of course not optimal. Feel free to adapt it to other purposes:

S = A((repmat(eye(size(A,1)),[1 size(A,1)]) *(kron(A,ones(size(A,1),1)) < kron(ones(size(A,1),1),A)))==0)'

A.