% SR_JACOBILOG1  This computes the first N recurrence 
%    coefficients alpha_k, beta_k, k=0,1,\ldots,N-1, to an 
%    accuracy of nofdig digits for the system of polynomials 
%    orthogonal with respect to the weight function 
%                 w(x)=(1-x)^a*x^b*log(1/x), 
%    using modified moments relative to the monic shifted 
%    Jacobi polynomials. The output variable ab is the Nx2 
%    array of the nofdig-digit recurrence coefficients, and 
%    dig is the number of digits required to achieve the 
%    target precision of nofdig decimal places using calculations
%    with precisions incremented in steps of dd digits. The
%    number dd in the first statement of the routine, as well 
%    as dig0, can be changed by the user as seen apprpriate.
%
function [ab,dig]=sr_jacobilog1(N,a,b,nofdig)
syms mom ab ab0 ab1 abn 
dd=10; dig0=nofdig;
ii=dig0-dd; 
maxerr=1;
while maxerr>.5*10^(-nofdig)
  ii=ii+dd; dig=ii
  mom=mmomjaclog(dig,N,a,b);
  abm=sr_jacobi(dig,2*N-1,a,b);
  abm(:,1)=(abm(:,1)+1)/2; abm(:,2)=abm(:,2)/4;
  if ii==dig0
    ab0=schebyshev(dig,N,mom,abm);
  else
    ab1=schebyshev(dig,N,mom,abm);
    serr=vpa(abs(ab1-ab0),dig);
    err=subs(serr);
    maxerr=max(max(err)); 
    ab0=ab1;
   end
end
ab=vpa(ab1,nofdig);