Finding the 3rd largest element in an array.

I've been thinking about sorting the array and extracting the 3rd element , or using max command while everytime i delete the data from a temporary array. But i'm wondering ... How do i find the 3rd largest element in an array using a loop/if or some sort of this stuff.

Thanks, Eran.

[Eran Sandman]

another question is - i get variables like '1.285e+4' . how can i sort this out ?

[Jan]

@Eran: See this to influence the output to the command window:

doc format

[Stephen23]

"i get variables like '1.285e+4' . how can i sort this out ?"

Sort what out? What is the problem?

Answer 1

[dpb]

Just go with the first option; the latter sorts the array three separate times. Unless the array size is humongous should be "adequately fast enough".

There's no problem, E formatting is simply an output artifact; doubles are doubles in internal memory storage and everything numerical is a double by default in Matlab unless you specifically cast to some other storage class such as single or in32 or the like.

Answer 2

[Jan]

x = rand(1, 1000);

% Method 1:
y = sort(x, 'descend');
y(3)

% Method 2:
y = x;
[dum, index] = max(y);
y(index)     = -inf;
[dum, index] = max(y);
y(index)     = -inf;
y3           = max(y)

% Method 3:
v = -inf(1, 3);
for k = 1:numel(x)
  v = sort([v(1:3), x(k)], 'descend');
end
v(3)