# summation's questions - Danish 1answer

499 summation questions.

### 1 Why these sums return the same result given seemingly they should be different?

0 answers, 83 views summation series-expansion
ThisSum[1, {k, 1, Infinity}, Regularization -> Dirichlet]gives -1/2, which is right. This ...

### 6 Relabeling of dummy variables

2 answers, 243 views simplifying-expressions summation
I have the following expressionF[p1, p2] a[p1] ** b[p2] - F[p1, p2] a[p2] ** b[p1]where ** is the non-commutative ...

### how can I solve this sum?

0 answers, 41 views summation assumptions
how can I solve this sum?Sum[1/(x[p]-x[q]),{p,1,l},p\[NotEqual]q]I tried these codes but not workin' ...

### Forcing nice positions of summation Σ 's under and overscript in FractionBox

Apologies if this has been asked before. The expression ...

### 1 Summation of terms involving contractions with 3 Levi Civita tensors

I am trying to evaluate this expression: $\epsilon^{abcdef}X^R_a X^S_b X^T_c X^U_d X^V_e X^W_f \epsilon_{RST} \epsilon_{UVW}$ where: $X = \frac{a^2 +b^2-1}{2a} \mathbb 1_6$ and I wrote this code ...

### Compute inner product of using a double sum vector [closed]

1 answers, 78 views replacement summation series-expansion

### 2 How to evaluate $\sum_{i=1}^{n-k+1} i \binom{n-i}{k-1}$ to get $\binom{n+1}{k+1}$?

0 answers, 49 views simplifying-expressions summation
I evaluate the following summation using mma (Version: 11.2.0.0): $$\sum_{i=1}^{n-k+1} i \binom{n-i}{k-1}$$ ...

### 1 Sum of part of a list that increases in length

I have a list of numbers whose length increases by 1 for every iteration of a loop. I need to take the sum of the last 5 elements of the list, and if the list's length is smaller than 1 I need to have ...

### 2 Nested ordered summation

1 answers, 53 views dynamic summation time-series

### 9 How can I compute a Kronecker sum in Mathematica?

3 answers, 973 views matrix summation

### Algorithm for Swapping indices and simplifying the summand in a double sum [closed]

Say we have something like $$\sum_{p}^N\sum_{q}^N \cos(p) \sin(q) - \cos(q)\sin(p)$$ usually, in the case like this, the indices p and q can be swapped, and the sum simplifies to 0. I have an ...

### 9 Problem with simplification KroneckerDelta

2 answers, 109 views bugs simplifying-expressions summation
Bug introduced in 8.0 or earlier and fixed in 9.0 I have: ...