how to random -1 and 1?

m=round(2*rand(8)-1)

the output:

m =

       1     0     0     1     0     0     0    -1
       1     1     0     0     1     1     0    -1
       0     1    -1     0     0     0     1     1
       1     0     0     1     0     0     1     0
       0     0    -1     1     1    -1     1     1
      -1    -1    -1     1    -1     0     0    -1
      -1    -1     1    -1     0    -1     1     0
       0    -1     0     1     1     0     0     0

but i don't want zero's output. can anyone help me clear this? thanks

Answer 1

[Azzi Abdelmalek]

m=randi(2,8)-1
m(~m)=-1

%or

m=randi([-1 ,1],8)
m(~m)=-1

%or

m=fix(rand(8)+0.5)
m(~m)=-1

[kjetil87]

you should be carefull about method 2 if you want it to be actually random, here there is a 2/3 chance of -1 , and 1/3 of +1.

[Azzi Abdelmalek]

Exact

[Tia]

ok, thank you for your advice

Answer 2

[Andrei Bobrov]

2*randi([0 1],8)-1

or

2*(rand(8)>.5) - 1

[Ahteshamul Haq]

Is the probabilty of getting -1 and +1 is 0.5. If not, kindly suggest a way to get it.

[James Tursa]

Yes, the probability of getting -1 and +1 is 0.5

Answer 3

[Mendi]

randsample([-1, 1],8,true)

Answer 4

[Francesco Sgromo]

-1^(randi(2))

[Stephen23]

(-1).^randi(2,8,8)

ans = 8×8

1 1 1 -1 -1 1 -1 -1 1 -1 -1 -1 -1 -1 -1 -1 -1 -1 1 -1 1 1 -1 1 1 -1 1 -1 1 1 -1 -1 -1 1 -1 1 1 -1 -1 -1 -1 -1 1 1 -1 -1 1 -1 -1 -1 1 1 1 -1 1 -1 1 1 1 -1 -1 -1 -1 1