[firedrake] Matrix multiplication in bilinear form

[Lawrence Mitchell]

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On 11/11/15 12:02, Anna Kalogirou wrote:
> Also, I don't really understand what the difference is between
> forming the matrix or taking its action...


So if you form the matrix, then you have A, and you can do things like
explicitly compute its inverse (using LU, say).

If you only give me the action, you don't have A, you just give me a
recipe for computing Ax if I give you x.  In this case, I don't know
what the entries of A are (so I can't explicitly compute its inverse).

Lawrence
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