function [nP,dP]=paderm(tau,r,m)
c(1)=1; 
for i=2:r+m+1, c(i)=-c(i-1)*tau/(i-1); end
w=-c(r+2:m+r+1)'; 
vv=[c(r+1:-1:1)'; zeros(m-1-r,1)];
W=rot90(hankel(c(m+r:-1:r+1),vv));
V=rot90(hankel(c(r:-1:1)));
x=[1 (W\w)']; 
dP=x(m+1:-1:1)/x(m+1);
y=[1 x(2:r+1)*V'+c(2:r+1)]; 
nP=y(r+1:-1:1)/x(m+1);