I have a matrix a=[1,2,3,4​..........​,20], Now I want to multiply every other element in a with -1 to get a=[1,-2,3,​-4........​........-2​0].

I have a matrix a=[1,2,3,4..........,20] Now I want to multiply every other element in 'a' with -1 to get a=[1,-2,3,-4................-20]. please help me with this......!!

[Azzi Abdelmalek]

Duplicate at

http://www.mathworks.com/matlabcentral/answers/105463-i-have-a-matrix-a-1-2-3-4-20-now-i-want-to-multiply-every-other-element-in-a-with-1-to

Answer 1

[Matt J]

 a(2:2:end)=-a(2:2:end);

[Ata Ul]

thanks man.........!! :D