q=w2q(w,a,b);

function q=w2q(w,a,b);
% q=w2q(w,a,b) converts frequencies
% into the q parameter used in Mathieu
% functions
if length(a)>1
  w=w(:); a=a(:)'; b=b(:)';
end
h=sqrt(a.^2-b.^2); q=(w*h/2).^2;