call every row of matrix in each iteration

Hi I have matrix a with 1 row and 300 columns. this matrix is composed of randomly elements between 1 to 300:

    a=randi(300,[1 300])

I reshaped it the matrix with 6 rows and 50 columns. I want to call in every time one of rows and use it like that:

for it=1:30
    show=it
    c=reshape(a,6,[])';
    [l1 l2]=size(c);
    rm=rem(it,l1);
    if it<=l1;
        k=c(it,:)
    elseif it>l1
        q=rm+1;
        k=c(q,:)
    end
    for i=k
        for j=k
            d=sum(k)
        end
    end
end

I have two question please. why is (d) written four times in each iteration? can I chage it? can I vectorize this code? thank you.