haqnomi

@ enthalpy, what are you talking about? My post was not about the topic you started. Are you replying for my topic? If yes then you may not understand this and if no then you are on the wrong place.

L= 1/2 (μ_(o ) γ_(i,0 ) γ_(i,0)+2P_o γ_(i,i)-αP_o γ_(i,i) γ_(j,j) ), Lagrangian density for acoustic waves in four dimensional notation. The form in vector notation can be found on the following article please: http://physics.stackexchange.com/questions/36249/speed-of-sound-and-the-potential-energy-of-an-ideal-gas-goldstein-derivation

Hi, all I would like to have understanding for the above notation please. The Lagrangian density is expressed for acoustic waves in four d notation. Further how to differentiate this Lagrangian for Lagrangian equation. I am very confused with indices mix up.