How can I find maximum before a certain element in my matrix
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For example B=[5 8 5 2 6 9 10] min(B)=2
I am looking for maximum point before min(B), which is 8 (not maximum of B elements, which is 10)
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Accepted Answer
Chad Greene
on 5 May 2015
Edited: Chad Greene
on 5 May 2015
B=[5 8 5 2 6 9 10] ;
[~,ind] = min(B);
maxB4min = max(B(1:ind))
=8
3 Comments
James Tursa
on 5 May 2015
~ causes the output variable for that spot (1st spot in this example) to be ignored.
[~,ind] = min(B);
is essentially equivalent to
[dummy,ind] = min(B);
clear dummy
Chad Greene
on 5 May 2015
Edited: Chad Greene
on 5 May 2015
If you wanted to know the minimum value in B and its index, you'd type
[minB,ind] = min(B)
minB =
2
ind =
4
which shows that the minimum value of B is 2, which is the fourth element in B. But we don't really need to know what the minimum value in B is, so the tilde tells Matlab to not bother writing the minimum value in B to a variable and gives us only the information we need:
[~,ind] = min(B)
ind =
4
More Answers (2)
Star Strider
on 5 May 2015
This works:
B = [5 8 5 2 6 9 10];
[~,ix] = min(B);
MaxBeforeMin = max(B(1:ix))
producing:
MaxBeforeMin =
8
The code searches for the index of the first value of the minium and returns it as ‘ix’. It then takes the maximum up to that index, and reports it as ‘MaxBeforeMin’.
Jos (10584)
on 5 May 2015
Just for fun, as a one-liner:
B = [5 8 5 2 6 9 10];
MaxBeforeMin = max(B(1:find(B==min(B),1,'first')))
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