Increment different rates in same for-loop

I have 3 different size matrix that are all supposed to be used in the same calculations. The issue I have is that matrix 1 is 8x1, matrix 2 is 4x1 and matrix 3 is 2x1. The increment rates that I need for M1, M2 and M3 are i, j and k respectively.

I need to for instance multiply M1(1,1) with M2(1,1) and M3(1,1) which is easy, but the next step would be

M1(2,1) * M2(1,1) * M3(1,1)

M1(3,1) * M2(2,1) * M3(1,1)

...

M1(8,1) * M2(4,1) * M3(2,1)

So for every iteration of the loop i increments by 1, j increments by half of i and k increments by a quater.

I've attempted to do it like so

for i = 1:8
   j = round(i/2);
   k = round(i/4);
   M1(i,1) * M2(j,1) * M3(k,1)
end

However, k assumes the values of [0 1 1 1 1 2 2 2] which is almost correct. How can I correct my small offset in my k increments - or better yet, is there a smarter way around this problem?

Thanks,

Niclas

[ANKUR KUMAR]

You value of k is [0,1,1,....]. While running the loop, it will throw this error,

Subscript indices must either be
real positive integers or logicals.

,for sure because you are using M3(k,1) later in the program, which never be possible in case of k=0;

Answer 1

[Niclas Madsen]

I've solved the issue using this format:

iter = [1 2 3 4 5 6 7 8; 1 1 2 2 3 3 4 4; 1 1 1 1 2 2 2 2];
for i = 1:8
    j = iter(1,i)
    k = iter(2,i)
    l = iter(3,i)
    M4(i) = M1(j,1) * M2(k,1) * M3(l,1)
end

Answer 2

[Stephen23]

Method one: a loop:

N = 8;
Z = nan(1,N); % preallocate
for k = 1:N
    Z(k) = M1(k) * M2(ceil(k/2)) * M3(ceil(k/4));
end

Method two: without a loop using indexing:

X = 1:numel(M1);
Z = M1 .* M2(ceil(X/2)) .* M3(ceil(X/4));

Method three: without a loop using repelem:

Z = M1 .* repelem(M2,2) .* repelem(M3,4)

For example, method two:

>> M1 = 1:1:8
M1 =
     1     2     3     4     5     6     7     8
>> M2 = 11:11:44
M2 =
    11    22    33    44
>> M3 = [111,222]
M3 =
   111   222
>> X = 1:numel(M1);
>> Z = M1 .* M2(ceil(X/2)) .* M3(ceil(X/4))
Z =
        1221        2442        7326        9768       36630       43956       68376       78144