# Tagged Questions

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### Symbolic evaluation of the sum of KroneckerDelta

I want to evaluate this simple expression $$\sum_n f(n)\delta_{mn} = f(m)$$ using this: Sum[KroneckerDelta[m, n] f[n], {n, Infinity}] However Mathematica ...
Can Mathematica do the following simple calculation? $$F(x_0, x_1, x_2, ...) \equiv \sum_n x_n^2$$ I want to do the symbolic calculation: $$\frac{\partial F}{\partial x_m} = \sum_n 2 x_n ... 0answers 47 views ### Expectation taking unusually long to evaluate I am trying to evaluate an expectation, but it is taking an extremely long time although the expression itself should not be too complicated. My code is ... 1answer 107 views ### Compute symbolic Expectation of a summation I am required to computed following Expectations : E[\displaystyle\sum\limits_{i=1}^N \frac{X_{i}}{N}] = \bar{x}_{0} & E[\displaystyle(\sum\limits_{i=1}^N \frac{X_{i}}{N})^2] = ... 2answers 97 views ### Assign a Distribution to a group of symbolic variable [closed] I'm looking to compute this Expectation : "i" represent a individual and h(i) is value. I would like the compute the Expected value of his value times the mean of the groups. Everything is unknown ... 2answers 378 views ### Problems with Symbolic summation over unknown values I'm having some real trouble with Mathematica wrongly evaluating various symbolic sums at the moment. I have this function:$$h_{ij}(x) = ...
When I do the double sum using the sigma notation I get $$1 + \sum_{n=0}^{\infty}\sum_{k = n}^{\infty} \frac{1}{(k+2)k!}$$ $1 + e - \cosh[1]$ When I do the sums as below, I get the expected ...