Finding the 3rd largest element in an array.

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Eran Sandman
Eran Sandman 2017-4-9
编辑： Stephen23 2017-4-9
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.
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Jan
Jan 2017-4-9
编辑：Stephen23 2017-4-9
@Eran: See this to influence the output to the command window:
doc format
Stephen23
Stephen23 2017-4-9
"i get variables like '1.285e+4' . how can i sort this out ?"
Sort what out? What is the problem?

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回答（2 个）

dpb
dpb 2017-4-9
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.
Jan
Jan 2017-4-9
编辑：Jan 2017-4-9
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)

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