removing max of a matrix

Hello

I have a matrix like this

if true

    A=[23,43,32,45,76,56,34,65,92,57];

end

now I want to find max and second max of it so after finding max of it, I want to remove it from matrix and then find another max (which would be second max) but I don't know how remove the first one. I use this:

if true

    B=A - [x];

end

but it subtract first max from all of matrix elements

Answer 1

[Image Analyst]

Try this:

A=[23,43,32,45,76,56,34,65,92,57, 92, 92, 92, 76]
% Remove max(es) from A
A(A==max(A)) = []
% Determine the second max from A
secondhighestNumber = max(A)

Note, using == lets it remove more than one occurrence of the max, unlike if you had used max() to determine the index of the max.

[M.S.A.A]

thank you for this answer, it was a really great helped

[Image Analyst]

If you want to remove any and all highest values, and any and all second highest values, regardless of how many of each there are, simply call the line twice:

A=[23,43,32,45,76,56,34,65,92,57, 92, 92, 92, 76]
% Remove max(es) from A
A(A==max(A)) = [] % Remove the four 92s.
A(A==max(A)) = [] % Remove the two 76s

Answer 2

[Star Strider]

This will remove the two largest elements of ‘A’ and leave the original order unchanged:

[As,idx] = sort(A,'descend');
A(idx([1 2])) = [];

A =
    23    43    32    45    56    34    65    57

[M.S.A.A]

thanks for your answer, but it's part of a project and I've been told to not use "sort" or I could simply use this:

if true
  B=sort (A);
disp (B(9:10))
end

[Star Strider]

My pleasure.

You did not specify that constraint in your original Question. You also did not mention that this was a homework problem. (We do not provide complete Answers to homework problems.)

Since I already posted a solution, this loop will produce the same result:

B = A;
for k1 = 1:2
    [~,idx] = max(B);
    B(idx) = [];
end
B                                   % Display Result

The result is the same as previously posted.

[Image Analyst]

MSAA asked to " find another max", not remove it. He also said to "remove the first one" and did not mention removing the second one. So that's why my solution removed any and all max values and found, but did not remove, the second highest value. My solution uses max(), not sort(). Please specify if max() is also not allowed.

http://www.mathworks.com/matlabcentral/answers/38787-what-can-be-programmed-without-any-built-in-functions

[M.S.A.A]

thanks for your solution, it was a great help