MacFormat 1994 August/August CD.bin/Shareware/Education/numericalmethods Folder/chap_4/pade.m

Text File | 1994-06-05 | 786 b | 33 lines | [MATF/MATL]

function [P,Q] = pade(C,n,m)
% [P,Q] = pade(C,n,m)
% The coefficient lists for Pn(x) and Qm(x) are computed.
% Some combinations of n and m are incompatible.
% C  is the list of Maclaurin coefficients, input.
% n  is the degree of Pn(x), input.
% m  is the degree of Qm(x), input.
% P  is the coefficient list for Pn(x), output.
% Q  is the coefficient list for Qm(x), output.
C = flipud(C);
A = C(1:n+m+1);
% First solve an  m x m  system for the Q's
Mq = zeros(m,m);
for j = 1:m,
  for k = 1:m,
    Mq(j,k) = C(j+k);
  end
end
for j = 1:m,
  B(j) = - C(n+j+1);
end
if m > 0, Q = Mq\B'; end
Q = [Q;1]';
% Second solve an  n+1 x n+1  system for the P's.
for j=1:n+1,
  P(j) = A(j);
  kmin = max(1,j-m);
  for k=j-1:-1:kmin,
    P(j) = P(j) + Q(m-(j-k)+1)*A(k);
  end
end
P = fliplr(P);