MATLAB: Accepting values into an array, then accepting new values by shifting left

accept newvalue and array leftMATLAB

I am calling a function in a different m file. I want this function to write newValues into an array. After 7 entries, the newValues need to be added to the end of the array and then shifted left in order to keep the values in order. Example: values accepted in the array are [1 2 3 4 5 6 7]. The new value is 8 which makes the array have values [2 3 4 5 6 7 8]. This is what I have so far….
function arrayWithLatestValues = fn_updateArray(newValue)
persistent A;
A = [A(2:end) newValue];
arrayWithLatestValues = A; 
end
this is my output im getting:
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0
     0     0     0     0     0     0     0

Best Answer

I'm guessing it is because of the persistent statement. Quote from the statement explanation:
" If the persistent variable does not exist the first time you issue the persistent statement, it will be initialized to the empty matrix."
If you have the vector as an input to the function, I believe the problem will be solved.
function arrayWithLatestValues = fn_updateArray(newValue,A)
A = [A(2:end) newValue];
arrayWithLatestValues = A; 
end
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