How to create impulse from timestamps?

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Hi i have an array x=[ 1 11 21 31 41 51 61 71 81 91]
i would like to create an impulse function of a=[0 1 0 0 0 0 0 0 0 0 0 1 0 0 ....]
my script is as follows

impfunc= zeros(1,max(a)
for n=1 : max(a)
if n==a
x(n)=1
end
end

but what i get is just impfunc = [ 0 0 0 0....]
any idea why it isnt working?