pdecgrad (Partial Differential Equations Toolbox)

The flux of a PDE solution.

[cgxu,cgyu]=pdecgrad(p,t,c,u)
[cgxu,cgyu]=pdecgrad(p,t,c,u,time) 
[cgxu,cgyu]=pdecgrad(p,t,c,u,time,sdl)

[cgxu,cgyu]=pdecgrad(p,t,c,u)

returns the flux, c

u, evaluated at the center of each triangle.

Row i of cgxu contains

Row i of cgyu contains

There is one column for each triangle in t in both cgxu and cgyu.

The geometry of the PDE problem is given by the mesh data p and t. Details on the mesh data representation can be found in the entry on initmesh.

The coefficient c of the PDE problem can be given in a variety of ways. A complete listing of all options can be found in the entry on assempde.

The format for the solution vector u is described in assempde.

The scalar optional argument time is used for parabolic and hyperbolic problems, if c depends on t, the time.

The optional argument sdl restricts the computation to the subdomains in the list sdl.