MATLAB: Find for sign changes

MATLAB

Columns 49 through 56
    0.8710    0.9483    1.0408    1.1538    1.2956    1.4796    1.7292    2.0885
Columns 57 through 64
    2.6538    3.6815    6.1847  119.1838 -118.8424   -5.8436   -3.3407   -2.3137
Above is part of my results. I need to find for value that changes from positive to negative. In the above data, after 119.1838(column 60) the -118.8424(column 61) appears. I need to find this value. Hoe can I do this?

Best Answer

find(x(1:end-1)>0 & x(2:end) < 0)
Another approach that might be close enough for your purposes:
find(diff(x>=0),1)
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