Sod Shock Tube problem is test case commonly used in computational hydrodynamics (CFD, SPH, etc) to see how well a certain computational approach works. It also helps in revealing the flaws in an approach (numerical scheme, etc). The implementation uses the initial conditions as proposed by G.A. Sod in "A Survey of Several Finite Difference Methods for Systems of Nonlinear Hyperbolic Conservation Laws", JCP (1978).