matlab code for a function that stores input in memory and gives 1 if it is not already present in memory and 0 if it is already present in memory

I want to design matlab code for a function that stores input in memory and gives 1 if it is not already present in memory and 0 if it is already present in memory. Forexample

if i wwrite compareinput('X'); (for first time it should give 1 & for all other iterations for same input it should give 0)

so far I tried this code but didnt worked out.

function [ Y ] = compareinput( X )
%UNTITLED2 Summary of this function goes here
%   Detailed explanation goes here
lastposition=0;
if lastposition~=X
    Y=1;

else
    Y=0;
end

lastposition=X;
end

Answer 1

[Walter Roberson]

http://www.mathworks.com/matlabcentral/fileexchange/21352-disk--memory-caching-store-objects-by-arbitrary-key