{ RCSid: $Id: glaze2.cal,v 2.2 2003/06/30 18:12:24 greg Exp $ } { glaze2.cal - double-pane fritted and low-E glazings Uses BRTDfunc type to get correct behavior. Oct. 2002 Greg Ward We only provide support functions for the nasty expressions spat out for dual-glazings by glaze.csh. } { Fresnel approximation } fresne = exp(-5.85*abs(Rdot)) - exp(-5.85); fr(r) = r + fresne*(1 - r); ft(t) = t*(1 - fresne); { glass reflectance and transmittance } rclr = fr(0.076); tclr = ft(0.883); { combined double-pane reflectance } cr(rf,t,rb) : rf + t*t*rb;