function h1=lanczos(ns,om)
ns2=2*ns;
H0=om/pi;
con=2.0*pi/(ns2+1);
i=1:ns;
omt=i*om;
omc=i*con;
h=(H0*sin(omt)./(omt)).*(sin(omc)./(omc));
tot=H0+2*sum(h);
H0=H0/tot;
h=h/tot;
h1(1:ns)=h(ns:-1:1);
h1(ns+1)=H0;
h1(ns+2:2*ns+1)=h;