Matrix

I have a matrix S1 and S2 which consist of +1, -1 and 0.

I want a matrix S such that it is +1 if there is +1 in both S1 and S2. -1 if there is -1 in both S1 and S2. 0 if anything else.

Answer 1

[Andrei Bobrov]

eg

S1 = randi([-1 1],10)
S2 = randi([-1 1],10)

solution

k= S1 + S2
S = (k==2) - (k==-2)

OR

S = (S1 == 1 & S2 == 1) - (S1 == -1 & S2 == -1)

MORE variant

S = (S1 == S2).*S1

or

S = (S1 == S2).*S2

Answer 2

[Wayne King]

One way

    x = [1 -1; 1 -1];
    y = [1 1; 1 -1];

    Z= zeros(size(x));
    Indx1 = find(x==1);
    Indy1 = find(y==1);
    Indxneg1 = find(x==-1);
    Indyneg1 = find(y==-1);

    Ind1 = intersect(Indx1,Indy1);
    Z(Ind1) = 1;
    Indneg1 = intersect(Indxneg1,Indyneg1);
    Z(Indneg1) = -1;