P0 0.1 "Source pressure amplitude"
beta 1 "Coefficient of nonlinearity"
N 5 "Number of harmonics to resolve"
r0 1 "Inner radius"
r_sh "r0*(1 + 1/(4*pi*beta*P0*r0))^2" "Shock formation radius"
a 0.7 "Relative distance to shock"
tau 0 "Retarded time"