Anders Logg <[email protected]> writes: >> It may be more effort than it's worth to distinguish contravariant, >> covariant, and invariant "vectors" in the type system, but doing so >> would fix these ambiguities. > > Perhaps, as one would also want to express terms like this one: > > [grad u]_n > > When u is a vector, I would want the above to be a contraction > (matrix-vector product).
Yes, naturally. It should contract the covariant index: (grad u)^i_j n^j > It seems messy to distinguish between these cases - scalar, vector, > matrix as arguments to jump(). Yes, but it is crystal clear and unambiguous if you distinguish covariance and contravariance (though we also need invariance).
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