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# Questions tagged [summation]

Questions using the Sum command, especially for series and other algebraic objects, and related functions such as SumConvergence

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201 views

### Conditional Summations

I am not a math major, but for a networking class, I am taking I am required to do summations for probability. I know the logic but I don't know the mathematical theory to make this work. Using ...
40 views

### Plot variations in geometric sum within prescribed range

I have a simple geometric sum: Sum[a^(j + 1), {j, 1, k}] which evaluates to (a^2*(-1 + a^k))/(-1 + a) ...
44 views

### Find closed form for roots of trig formula

I have the expression Sum[(2 j \[Pi] Sin[(2 j \[Pi] x)/(r + 1)])/(r + 1)^2, {j, 0, r}] == 0 I want to find the roots in terms of ...
161 views

### Cumulative total of columns in a matrix or table

I have the following: matrix1 = {{a, b, c, d}, {e, f, g, h}, {i, j, k, l}, {m, n, o, p}} (Note that it's the data that matters, not the fact it's defined as a ...
51 views

### Summing results of a table

I have a simple table: example1 = Table[N[x^(x/r), 5], {r, 1, 10}, {x, 1, 10}] I want to create a new table ...
64 views

### How can I get the simplest result of this sum?

I am trying to find the sum $$\sum _{k=1}^n \frac{k+1}{(k-1)!+k!+(k+1)! }.$$ I tried Simplify[Sum[(k + 1)/(( k - 1)! + k! + (k + 1)!), {k, 1, n}]] and got ...
185 views

### Sum over multiindex

I would like to calculate a sum over some multi-indices, that follow a specific pattern. $$\sum\limits_{1\le i_1<i_2<...<i_k\le N} A(k,i_1, i_2, ..., i_k).$$ $A$ is a fix expression of the ...
110 views

### Total of summed objects of unequal lengths

I obtained {1}+{0,2}+{0,0,1}from a calculation. Now I need to sum these objects and reach 4. How can I do this? I tried ...
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### Summing over a list

I intend to sum a series over two lists which I generate myself. However, my code is not working. What is the best way to do this? Thanks. Find my code below ...
68 views

### Solving a sum involving a distribution

Can anyone help me solve this sum? ...
59 views

### how can I solve this sum?

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' ...
41 views

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

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

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

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

### 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 ...
65 views

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### 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 ...
119 views

### Problem with simplification KroneckerDelta

Bug introduced in 8.0 or earlier and fixed in 9.0 I have: ...
452 views