% SR_HALFRANGEHERMITE  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 half-range Hermite polynomials \\
%    orthogonal with respect to the weight function \\
%           w(x)=exp(-x^2)  on R_{+}. \\
%    The output variable ab is the Nx2 array of the \\
%    nofdig-digit recurrence coefficients, and dig is \\
%    the number of digits required to achieve this \\
%    target precision \\
%
function [ab,dig]=sr_halfrangehermmite(N,nofdig)
syms mom ab ab0 ab1 
dd=10; dig0=nofdig;
i=dig0-dd; 
maxerr=1;
while maxerr>.5*10^(-nofdig)
  i=i+dd; dig=i;
  mom=momhalfrangehermite(dig,N);
  if i==dig0
    ab0=schebyshev(dig,N,mom);
  else
    ab1=schebyshev(dig,N,mom);
    serr=vpa(abs(ab1-ab0),dig);
    err=subs(serr);
    maxerr=max(max(err)); 
    ab0=ab1;
   end
end
ab=vpa(ab1,nofdig);