How to replace a range in one array at a specific location using the value of another array to determine where?

I have two arrays (both are 1 column):

1. ArrayZeros - this array is filled with 400,000 zeros.
2. ArrayInput - this array has 20 values.

My goal is iterate through ArrayInput and use those numbers to determine were in ArrayZeros I should replace with the number '4'. This number in ArrayInput would be the start location, and I want to replace 20 0's with 20 4's. For example, if ArrayInput's first number is 8 then I want to go to the eighth location in ArrayZeros and replace with a 4 and continue until the 28th zero. This will change ArrayInput from 8-28th location to 4's. I would want to keep iterating through ArrayInput and continue to change ArrayZeros.

Answer 1

[the cyclist]

I believe this does what you need.

ArrayZeros = zeros(400000,1); %this array is filled with 400,000 zeros.
ArrayInput = [5 40 230]; % this array has 20 values (but using 3 values to illustrate).

PositionsToFill = 20;

for na = 1:numel(ArrayInput)
    anchor = ArrayInput(na);
    ArrayZeros(anchor:anchor+PositionsToFill-1) = 4;
end