how can i negative all rows in a matrix?just rows

how can i negative all rows in a matrix?just rows

[Azzi Abdelmalek]

What does that mean?

[John D'Errico]

One can only presume that the OP is asking how to negate an array. But then why would that negate only the rows, and not the columns?

[Jan]

@fariba amini: Please post a small example which explains, what "negative rows" means and how if differs from negate the elements.

Answer 1

[Andrei Bobrov]

Let a - your array

a = [-4     0     1    -2    -3
    -3    -5    -5    -2    -1
     3     2    -3     1     0
    -1     3    -5     2    -4
     2     1    -5    -4    -4
    -4    -1    -2    -1    -1
    -2     1     1    -1     3
     3    -2    -3     0    -2
     2     0     3     1     0
     3    -4    -5     1    -3];

out = a(all(sign(a) == -1,2),:);

[Jan]

This is finding all rows, which contain negative values only.