... by1
The standard seven-point diffusion operator does not account for a flux source term, , so that is omitted from the current discussion.
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... faces.2
In general, for multiple dimensions the scheme has nd + 1nc + nb/2 unknowns, where nd is the number of dimensions.
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... quartic3
The method is exact for linear solutions, so no improvement is achieved by refining the mesh in that situation.
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