Finding location of change of signs of a matrix's elements

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Volkan Yangin
Volkan Yangin 2017-2-18
评论： MA-Winlab 2019-4-7
Hi everbody, I have a matrix like this:
A=[0 0 0 0.33 0.33 0.33 0 0 0 -0.33 -0.33 -0.33 0 0 0];
How can i find location of change of signs? I get an error while using find and diff command. I think, i have made a mistake because of the < and > symbols. May you help me? Thanks.

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Walter Roberson
Walter Roberson 2017-2-18
find(diff(sign(A)))+1
to return the locations of the beginning of the new sign.
Note that this includes changing to 0, as 0 has a different sign than positive numbers or negative numbers.
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MA-Winlab
MA-Winlab 2019-4-6
@Roberson, I tried your approach for finding the locations of change from 0 to 1 and from 1 to 0, but they are in one array.
So, if I have this array and want to find the locations of change from 1 to 0 (returned in an array) and the locations of change from 1 to 0 (returned in a SEPRATE array), how can I modify this line?
Thank you
A=[0 0 0 1 1 1 0 0 0 1 1 1 0 0 0];
MA-Winlab
MA-Winlab 2019-4-7
Update
I figured out how to do that (in my case, the vector of 0s and 1s has an even number):
OpenClose = find(diff(sign(A))) + 1;
OneToZero = OpenClose(1:2:end)
ZeroToOne = OpenClose(2:2:end)

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