Index in position 2 exceeds array bounds. Index must not exceed 1. - correctly indexing a changing element in a matrix

So I'm trying to write a for loop that indexes a specific element of a matrix, but the element being indexed changes for each loop. Here's what I have

for tt=19:-1:1
    for j=1:15
        for k=1:15
            for i=info
                if M(j,k)>0
                    p(j,k)=0.9;
                elseif M(j,k)<0
                    p(j,k)=0.1;
                elseif M(j,k)==0
                    p(j,k)=0.5;
                end
                
        Fd(i,j,k)= b*(... 
            m1*(...
                p(y(j),z1(k))*(n1*Fd(xp(:,i),zp(j),y(k),tt+1) + (1-n1)*Fd(xpp(:,i),zpp(j),y(k),tt+1))+...
                

y and z1 are vectors that correctly call upon the element I want when using it in the matrix e.g.

        >> M(y(1),z1(2))

ans =

     2

I have the vectors written so that they don't go beyond the matrix boundary. z1 = z+1 and the matrix boundary is 15, but I've capped the vector so that z1(15) just returns 15.

I think the problem is coming from my use of p trying to call the element. Any insight as to why it's not working?

[Cris LaPierre]

The error is easy enough to explain, but without a working example, it's hard to say what you should change.

Somewhere your column index exceeds the number of columns of the variable, which the error says is 1. Maybe you are working with a column vector instead of a row vector?

a=(1:5)';
% works
a(3,1)

ans = 3

% your error
a(1,3)

Index in position 2 exceeds array bounds. Index must not exceed 1.