problem with if in a matrix

I have a matrix g:

>> g=sin((1:1:10)'*(1:1:2))

g =

    0.8415    0.9093
    0.9093   -0.7568
    0.1411   -0.2794
   -0.7568    0.9894
   -0.9589   -0.5440
   -0.2794   -0.5366
    0.6570    0.9906
    0.9894   -0.2879
    0.4121   -0.7510
   -0.5440    0.9129

when I add the two columns together I get

(g(:, [1])+g(:, [2]))

ans =

    1.7508
    0.1525
   -0.1383
    0.2326
   -1.5029
   -0.8160
    1.6476
    0.7015
   -0.3389
    0.3689

I want matlab to return the results of the first column when the results are positive and of the second column when the results are negative, so I tried:

if(g(:, [1])+g(:, [2]))>0

g(:, [1])

else

g(:, [2])

end

but that just gives me the results of the second column.

Answer 1

[Azzi Abdelmalek]

idxn=sum(g,2)<0
out=g(:,1);
out(idxn)=g(idxn,2)