??? Input argument "n" is undefined. Error in ==> dd1 at 4 h=zeros(1, length(n)); how to solve this error

function h=dd1(n)
h=zeros(1, length(n));

h(n==0) = 1;

n=-10:10;
h(n)=dd1(n-3)-2.7083*dd1(n-4)+4.1861*dd1(n-5)-3.0451*dd1(n-6)+0.73071*dd1(n-7);
stem(n, h)
xlabel('n')
ylabel('Delta Function')

please help

Thank you.

[Stephen23]

Call dd1 with an input argument.