How to convert all array values into negative ones?
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I have an array A:
A = [2; 3; 5; -8; 9; 1; -1]
how do I convert it into an array whose values are all negative? So as to obtain B:
A = [-2; -3; -5; -8; -9; -1; -1]
Thanks!
采纳的回答
A = [2; 3; 5; -8; 9; 1; -1] ;
A(A>0) = -A(A>0)
更多回答（3 个）
You can do like.
A = [2; 3; 5; -8; 9; 1; -1];
A = -(A.*A).^0.5;
A = [2; 3; 5; -8; 9; 1; -1]
%way #1
A(A>0) = -A(A>0)
%way #2
A = [2; 3; 5; -8; 9; 1; -1]
A = -abs(A)
So many ways. Don't forget the simple solution:
A = [2; 3; 5; -8; 9; 1; -1]
B = -abs(A) % this makes all of the signs positive, then negates the entire lot
Or we could do this:
C = -sign(A).*A % this is similar to the use of abs
Those ways act on the entire array. In order to act only on those that have the wrong sign and do it effectively in place, the standard MATLAB solution would be this:
A(A > 0) = -A(A > 0)
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