function [xnu,L] = louvl(S,nu)
% Routine to use Liouville operator matrix to generate
% absorption coefficient for molecular lines.  To be used
% for overlapping line problem eventually.  Line profiles
% are Lorentzian.  S = vector of line strengths,
% nu = vector of line center wavenumbers.
% To use:  [xnu,L] = louvl(S,nu);
% by D. Holmgren, Aug 1 95
% Checked out with Sun Matlab.
xlo = input('Lower wavenumber limit: ');
xhi = input('Upper wavenumber limit: ');
np = input('Number of points: ');
xnu = linspace(xlo,xhi,np)'; S1 = diag(S); L = zeros(np,1);
for k = 1:np
 L(k) = -imag( trace( S1*inv( diag( xnu(k)-nu+0.1*i ) ) ) )/pi;
end
plot(xnu,L)
xlabel('Wavenumber (cm-1)')
ylabel('L(nu)')
title('Absorption coefficient spectrum')
%shg