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Aug
10
revised The fastest way of raising indices of high rank tensor
Length@Dimensions -> ArrayDepth
Aug
9
answered Ways to compute inner products of tensors
Aug
9
revised The fastest way of raising indices of high rank tensor
optimize transposition list
Aug
9
comment The fastest way of raising indices of high rank tensor
@g3n1uss Notice there is a type in the first computation: it should be ...Sum[F[[i,j,k,l]]...
Aug
9
answered The fastest way of raising indices of high rank tensor
Aug
9
answered Adding labels to graphics
Aug
9
comment Adding labels to graphics
The definition of vsorted is missing. Is it the same as vectors?
Aug
9
comment Solving a system of first order differential equation with DSolve
And what is $s$? Is it another constant?
Aug
9
answered Why does the Derivative function not appear in the tree form?
Aug
4
comment Injecting a sequence of expressions into a held expression
Indeed, there is an implicit Sequence: try {#}&@Unevaluated[1, 2] // Trace.
Aug
3
asked Cannot Block Plus
Aug
3
comment MatrixExp of a complex matrix of size about 10000 by 10000
@user45765 If all you need to do is exponentiate and take the trace, then you can use Tr@Exp@Eigenvalues@A. In fact, the eigenvalues of $e^A$ are the exponentials of the eigenvalues of $A$.
Aug
3
comment Redefining a built-in operator
@Omegaman There is exactly the same difference that there is between = and :=. The ^ just stands there to signal that you want to associate the whole definition to the symbol z and not ||. Define f1[g1[t_]] ^= Expand[t^2] and f2[g2[t_]] ^:= Expand[t^2] and run f1[g1[t+1]] and f2[g2[t+1]]. You can check why it does what it does by looking at ?g1 and ?g2.
Aug
2
comment How to avoid nested With[]?
I suggest the variant LetL /: (assign : SetDelayed | RuleDelayed)[lhs_, rhs : HoldPattern[LetL[{__}, _]]] := Block[{With}, Attributes[With] = {HoldAll}; assign[lhs, Evaluate[rhs]]];, so that one can also use it with RuleDelayed as in Range[10] /. x_Integer :> LetL[{y = x}, -y /; y <= 5].
Mar
20
awarded  Yearling
Oct
13
awarded  Nice Answer
Sep
30
awarded  Explainer
Mar
20
awarded  Yearling
Aug
5
asked Det and MatrixRank freezes on SparseArray with nonzero default value
Jul
29
awarded  Necromancer