Questions tagged [indexing]
The indexing tag has no usage guidance.
15
questions
1
vote
1answer
35 views
Index an array with condition
I have a list like the following:
list = {{1, 11}, {2, 7}, {4, 2}, {7, 9}, {-2, 1}};
I would like to select those entries whose second elements are greater than 2, ...
0
votes
0answers
19 views
Indexing list returned by a function [duplicate]
How do I access elements of a list that is returned by a function?
My function that returns the list is:
b[x_] := (Return[{x, x/2}];)
Then when I try to reference ...
1
vote
1answer
28 views
Computing a Transformation then visualizing with TransformedRegion Function
I have some function $\psi$, I compute the transformation $T = \vec{x} - \nabla \psi$. I'd like to visualize the action of $T$ on a square centered at the origin.
The mathematica website shows some ...
1
vote
0answers
72 views
Can you create an indexed list of all Wolfram functions within a notebook? [closed]
Can you create a summary list of all Wolfram functions used within a whole notebook? Searched long and hard- no clear documentation found.
6
votes
1answer
92 views
Undefined Indexed Variable
I searched already a lot about indexed Variables, and it tends to be the most applicable way to use tensor notation. But I am having a hard time to solve for undefined indexed variables:
Here my ...
2
votes
1answer
81 views
Plot the indices of the background Matrix instead of the calculated values
I want to create a background 60*100 matrix and insert inside it the calculated values, for example
...
0
votes
1answer
32 views
Is it possible to renumber a notebook without rerunning it?
When I prepare a notebook to share with others, I like the numbering of the code cells to start from 0 and to increment predictably to make them more readable, but the only way I know to do this is by ...
1
vote
1answer
33 views
How does Mathematica evaluate sums where the upper limit of the index is not an integer?
I am interested in the way Mathematica evaluates sums where the upper limit of the index is not an integer - i.e., sums that are some sense mathematically meaningless. For example:
...
2
votes
2answers
49 views
How to identify index intervals that contain a value?
I have a really simple question but, sorry, I can't seem to find an elegant solution to other than iterating through. I have a list of indices, and a relative list of values, I would like to extract ...
6
votes
2answers
108 views
How to create a nested list of variable depth with indexed elements
i want to obtain this definition of a nested list
t = Table[C[i, j], {i, 3}, {j, 3}]
with arbitrary depth,
...
6
votes
2answers
207 views
Contracting indices in lists
Using an answer to this question (Working with Dirac Gamma Matrices using FeynCalc - A simple problem), I defined
...
2
votes
1answer
100 views
how to add labels of points next to it based on index in ListPlot
I have a list of some points. I plotted each point and its closest surrounding points.
...
4
votes
1answer
65 views
Replace pattern with the number of matches so far
I want to replace a n-th pattern match in an expression with n. This is a very simple task, though it appears very hard to find an elegant implementation.
For example, with input
...
1
vote
1answer
52 views
Sum index in function collides with input variable
When I enter the following:
Clear["Global`*"]
Func[f_, xx_] := Sum[D[f, xx[[s]]], {s, 1, 2}]
Func[x^2 + y^2, {x, y}]
Func[x^2 + s^2, {x, s}]
The first function ...
5
votes
4answers
254 views
How to search within notebooks on Windows 10?
I have a lot of notebooks scattered in my downloads, documents and desktop folder. I have all the required locations on Windows indexing options but if I look at Advanced Options and File Types and nb ...
