k_air acpr.omega/c_air Wave number a0 i*acpr.omega*v0 Piston acceleration P intop_piston(2*r*p/a^2) Mean value of pressure on piston z0 P/v0 Piston impedance eta0 z0/(rho_air*c_air) Normalized piston impedance alpha0 real(atanh(eta0))/pi Hyperbolic piston impedance factor beta0 imag(atanh(eta0))/pi Hyperbolic piston impedance factor alphaL alpha0 Hyperbolic radiation impedance factor betaL beta0-k_air*L/pi Hyperbolic radiation impedance factor etaL tanh(pi*(alphaL+i*betaL)) Normalized radiation impedance zL nojac(etaL)*rho_air*c_air Radiation impedance alpha0_ana alphaL_ana(k_air*a) Hyperbolic piston impedance factor beta0_ana betaL_ana(k_air*a)+(k_air*L/pi) Hyperbolic piston impedance factor eta0_ana tanh(pi*(alpha0_ana+i*beta0_ana)) Normalized piston impedance factor z0_ana eta0_ana*rho_air*c_air Piston impedance