function ab=sr_logistic(dig,N)
%SR_LOGISTIC_OPS Recurrence coefficients for the logistic 
%weight function
%   AB=SR_LOGISTIC(DIG,N) generates in DIG-digit arithmetic 
%   the Nx2 array AB of the first N recurrence coefficients for
%   the weight function w(x)=exp(-x)/(1+exp(-x))^2 on [-Inf,Inf]. 

digits(dig); 
ab=vpa(zeros(N,2)); s1=vpa(1); spi2=vpa(pi)^2; s1=vpa(1); s4=vpa(4);
k=vpa(1:N-1);
ab(:,2)=[s1 spi2*(k.^4)./(s4*(k.^2)-s1)]';
