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5
votes
3answers
335 views
Ways to compute inner products of tensors
One way to evaluate the following sums is combining Table and Sum:
$u_{abcd} = \sum_{e=1}^3 v_{aeb}w_{ced}$
$q_{ab} = \sum_{d,e=1}^3 v_{d e a}w_{deb}$
It will look like
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9
votes
4answers
357 views
how to differentiate formally?
I have been wrapping my head around this for a while now and I have not found a solution so far.
I want to work with an arbitrary number of variables in mathematica and use some built in functions.
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1
vote
2answers
164 views
Sum of Multinomial Coefficients
Basically I want to write a function to compute the following sum
$f(m,L):=\sum_{0\leq k_1,\cdots, k_n\leq m} \binom{m}{k_1,k_2,\cdots k_n}$ and $supp(k)=L \subseteq \left \{ 1,...,n \right \}$
I ...
