index must be a positive integer or logical.

I am getting the following error while running the code:

Attempted to access (1,NaN); index must be a positive integer or

logical.

Error in

sh_row(i,(col+j-k(i)))=rgb(i,j);

% IF k is even right shift row else left shift row%%%%%%%%%%%%%%%%%
for i=1:1:row
    for j=1:1:col
        if(mod(k(i),2)==0)
            if((j+k(i))<=col)   %shift right of row
               sh_row(i,j+k(i))=rgb(i,j);
               row_shift_even(i,j)=j+k(i);
            else
               sh_row(i,(j+k(i)-col))=rgb(i,j); %HERE
               row_shift_even(i,j)=(j+k(i)-col);
            end
        else
            if((j-k(i))>=1)       %shift left of row
                sh_row(i,j-k(i))=rgb(i,j);
                row_shift_odd(i,j)=j-k(i);
            else
               sh_row(i,(col+j-k(i)))=rgb(i,j);
                row_shift_odd(i,j)=col+j-k(i);
            end
        end
    end
end

[Walter Roberson]

You had bolded the line

sh_row(i,(j+k(i)-col))=rgb(i,j);

as if it were the one the error is occuring on, but the error is occuring further down, at

sh_row(i,(col+j-k(i)))=rgb(i,j);

[Walter Roberson]

We have no information about the range of values in k(i). If k(i) were large then j-k(i) could be negative, and so would fail the j-k(i)>=1 test. If it were large enough, then col+j-k(i) could be negative or 0 in the line the problem is occuring on.