matalb convolution with memory

hi,

i have an impule function h[n]=δ[n]+3δ[n-1]-h[n-1]

x[n]=rectangular...

how can i convolute the 2 sequences? how can i define in matlab h[n] when i have h[n-1] also?

Answer 1

[John D'Errico]

This is not a job for convolution, since h lies on both sides of the equality, with a lag on h.

Use filter instead.

You should see this fits trivially into the form that filter solves:

Y = filter(B,A,X) filters the data in vector X with the
    filter described by vectors A and B to create the filtered
    data Y.  The filter is a "Direct Form II Transposed"
    implementation of the standard difference equation:
 
    a(1)*y(n) = b(1)*x(n) + b(2)*x(n-1) + ... + b(nb+1)*x(n-nb)
                          - a(2)*y(n-1) - ... - a(na+1)*y(n-na)