# Questions tagged [index]

Questions about functions with intrinsic part index such as SparseArray, Part and Indexed or iteration variable indexes such as MapIndexed, Sum and Product.

9 questions with no upvoted or accepted answers
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### Efficiently get positions of Query results

I have some very large Datasets. Is there any efficient method of getting the positions of results found in a Query? That is, without using ...
• 3,780
117 views

### Typography of Mixed Tensor Index Notation

How can one properly and quickly write a mixed "tensor" such as $\Gamma{}_{1}{}^{2}{}_{3}$? Shortcuts such as esc Gamma esc, Ctrl+^, Ctrl+_ are prefered. I intendd to use this in an inline equation ...
• 1,883
763 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 ...
123 views

### ParallelDo with doubly-indexed iterators

What is the reason that ParallelDo works with singly-indexed iterators, but not doubly- or more-indexed iterators? For example, the code ...
1 vote
368 views

### Assigning Values of Indexed Variables to Arrays

New to mma. I have assigned the results of using Solve to solve 5 variables to 5 indices of a new variable: ...
• 63
1 vote
115 views

### Index change in a recursive definition

Assume I have the following recursive definition: ...
• 11
39 views

### One as Subscript and Supersripts

I am trying writing code with a lots of symbols and their products. There is an issue with the appearance of "1" as an index. e.g. Subscript[[Delta], 1 n] Why "1" does not appear ...
• 575
28 views

### How to define an index list of local variables for arbitrarily long

Suppose initially I have a list that looks like list1 = {A, B, C} where the elements A, B, C are all matrices. I want to substitute all the three elements by list1 ...
50 views

### Defining list of data

I need to define a list of parameters A[i] where i runs from 1 to some integerN. The ...