Distribution function (physics)

In molecular kinetic theory in physics, a system's distribution function is a function of seven variables, f ( t , x , y , z , v x , v y , v z ) {\displaystyle f(t,x,y,z,v_{x},v_{y},v_{z})} , which gives the number of particles per unit volume in single-particle phase space. It is the number of particles per unit volume having approximately the velocity v = ( v x , v y , v z ) {\displaystyle \mathbf {v} =(v_{x},v_{y},v_{z})} near the position r = ( x , y , z ) {\displaystyle \mathbf {r} =(x,y,z)} and time t {\displaystyle t} .

Source: Wikipedia — Distribution function (physics) (CC BY-SA 4.0)