Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.

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2
votes
2answers
215 views

Create list via checkboxes

I am trying to achieve the following: Three (dynamically updated) Checkboxes (a, b and c) can be toggled on or off individually. Depending on their status, a ...
1
vote
1answer
118 views

Format Preservation of FullSimplify on Indexed System of Autonomous Equations

I currently have a large system autonomous differential equations. I've indexed a more managable dummy system of identical form, using Part to reference each ...
13
votes
1answer
161 views

Why changing list's head takes time?

Consider AbsoluteTiming[Range[10^7];][[1]] 0.035000 and AbsoluteTiming[HoldComplete @@ Range[10^7];][[1]] ...
4
votes
1answer
65 views

Optimizing List Multiplications

I've got a list manipulation optimization problem. Consider a two-dimensional nxm list list1, and a three-dimensional nxmxm list, ...
1
vote
0answers
59 views

Sorting Eigensystems [duplicate]

SO I have this code: ...
3
votes
3answers
193 views

Plot sublists as different colors

I have one big list with many sublists inside. All sublists consist of three numbers. For example: ...
2
votes
0answers
168 views

Exporting Specific Cells of Many Workbooks into One using Mathematica

I currently have a large number of detailed files from which I would like to extract certain cells' information to make an Archive spreadsheet. There are approximately 9 parameters of each ...
3
votes
1answer
137 views
3
votes
1answer
127 views

Filtering the elements of an array to split them into two categories

So, I am new to Mathematica, and I am trying to write something that involves taking values from one array and separating them into two different arrays. My code for doing this is: ...
1
vote
2answers
126 views

Counting a cardinality of a subset satisfying special property

Suppose that we have a set of 9 2-dimensional vectors $c$ by m=3; n=2; c=Tuples[Range[m],n]; We want to define a subset $S$ of vectors in $c$ by the following: ...
3
votes
2answers
586 views

Function returning Null along with other unexpected expressions

When I use some function, at the end along with the output I get some NULLs returned that I don't understand the reason for and are highly undesirable. For example, when I define the reversal of list ...
3
votes
1answer
177 views

Generating a list of all factorizations

What is the best way to generate a list of all factorizations of some number $n$? I'm quite new to Mathematica so this might be obvious. I have been trying some basic stuff with ...
3
votes
1answer
183 views

Indexing of Large Autonomous System of Equations for Use in NDSolve

I currently have a list of ~150 autonomous DAE's (differential-algebraic equations) that I need to be able to work with using NDSolve. Fortunately I already have ...
5
votes
3answers
207 views

Applying a function with the HoldAll attribute inside NestList

I'm trying to write an update function, which can be applied to a list and then to NestList it. As the function has to manipulate the given variable I figured I ...
2
votes
4answers
717 views

How can I create a list of functions?

Can anyone tell me, how to create a list of functions? I've tried the following code, but it doesn't work. ...
2
votes
1answer
111 views

Flat function with repeated sequence

There are functions like Join[ ] that accept a variable number of arguments. Join is a flat function, as the order of arguments ...
9
votes
1answer
265 views

Efficient way to solve equal sums $x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k$ with Mathematica?

I need to solve the system of equations, call it $S_1$, in the integers $$x_1x_2x_3x_4x_5 = y_1y_2y_3y_4y_5$$ $$x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k,\;\; k= 2,4,6$$ I used a very ...
5
votes
4answers
212 views

Tricky selection of elements based on their position

I need to make a list of some elements from a 4D array with dimensions 4x4x4x4. I need to select the elements based on their position in the following way: name an element e(x,y,z,w); I need all the ...
1
vote
2answers
108 views

Can you form a list with elements which are terms from an equation?

Is there a command that takes an equation as an input and creates an output with a list of terms in the original equation? Something like: ...
0
votes
0answers
39 views

Generating partitions of a set with a specified size of the parts [duplicate]

I tried the following (inspired by the answer here) myList = {a, b, c}; Needs["Combinatorica`"]; SetPartitions[myList] and I got this answer, ...
2
votes
2answers
170 views

How to select elements from a 4D Array?

I am very new to Mathematica (first time!) and I'm already having troubles with arrays. I basically have a 4D tensor, that is a matrix (call it M) which has for ...
0
votes
1answer
134 views

Monitor the list for changes

I wrote a function to monitor the list of variable. What it does is if the variable in list change, the changed variable will be separated from others. check the function and output ...
1
vote
1answer
230 views

How do I operate on a set of ordered pairs? [closed]

I have a calculation that will give me a lot of ordered pairs. For each such pair in a list, I want to square the elements and add them together. Here is an example of the kind of list I have ...
3
votes
2answers
207 views

How to replace Do loops by Inner

I need to replace Do loops by something else because it takes forever with big programs. I have been hinted towards Inner, but ...
7
votes
3answers
276 views

Making large tables easy to read with frozen headings and scrollbars [duplicate]

I would like to represent a table containing a large amount of information in such a way that I can (a) use scrollbars and (b) have table headings that don't scroll off the screen [just like the Free ...
6
votes
1answer
111 views

How does `LongestCommonSubsequence` work?

When I recently came across this posting about LongestCommonSubsequence I was curious about how the function worked. ...
4
votes
2answers
306 views

Linear regression in a chosen range of points

Hi I'm absolutely newbie in Mathematica and have following problem: My list looks like {{50, 0.75}, {51, 0.76}, ..., and I want to choose a range out of my ...
0
votes
2answers
468 views

Finding max, min, and closest root of two dimensional data

I have some data that is two dimensional (traditional (x, y) format) as so: var = {{x1, y1}, {x2, y2}, {x3, y3}} I would like to search through that large list ...
10
votes
6answers
723 views

Multiplying two dimensional data by a constant

I have a list of lists of the form: {{1, 2}, {2, 4}, {2, 8}} But I want to multiply only the second dimension of that data by a constant. I know I could do this ...
1
vote
2answers
185 views

Plotting array of vectors with conditions

Given data in the form list={{{1,2},{3,4},{5,6}},{{7,8},{9,10},{11,12}},...} a matrix where elements are 2-element vectors, what is a efficient way to plot this ...
0
votes
1answer
117 views

joining lists based on content

I have lists created by other processing steps, which are basically constituted by elements like this: ...
3
votes
3answers
161 views

Picking certain pairs according to a condition [duplicate]

I'm a Mathematica beginner and can't find out a solution to my problem. I have a list of pairs of numbers, for example something like this, but much longer: list={{2., 3.}, {3., 2.}, {5., 4.}, {4., ...
2
votes
1answer
109 views

Expand List Operation

On applying a multiplication and subtraction on a list, like so: x = 2y - 4; Where y is a list containing fractions of complex numbers generated from dynamic ...
5
votes
1answer
147 views

question about Inner [duplicate]

question1: (code 1 something wrong, Why? and how to overcome this to achieve the next code's effect) ...
3
votes
4answers
145 views

Rearranging a set of numbers

I have this set of numbers, that is a range of prices (ie 6-10) and a quantity of products (5) ...
3
votes
1answer
254 views

Create a table with inline conditions

I am trying to create a table with conditionals inline. For example, I'd like to create a 2 dimensional table like this: ...
2
votes
2answers
286 views

How to populate a table using a rule replacement

I am trying to populate the rows and columns of a table by using a rule replacment. To generate a table that looks like this For example Sc would be row 1, column 1. An example of a record looks ...
1
vote
1answer
249 views

How to normalize parts of matrix elements?

To normalize the last 2 or more columns of a matrix, ...
17
votes
5answers
715 views

Instruct a Table to only evaluate until a condition is fulfilled

I am looking for the way of building a Table of pairs of numbers in a fast way. My true table evaluates huge functions, and I see no way and reason to show those cumbersome expressions here. Let us ...
0
votes
1answer
85 views

Breaking up data and finding independence

Suppose I have the list with elements (either 1 or 4 as the last digit) as follows: ...
0
votes
3answers
378 views

Pass an empty list object into a function and dynamically generate its list elements

I have another question on passing a list which needs to be generated dynamically. (Sorry for posting two questions in one day...) I did some search and found a similar post here, but I think it was ...
0
votes
0answers
120 views

How can I solve this system of functional equations?

I would like to use Mathematica to find maps a, b, c, d, e, f such that ...
1
vote
1answer
141 views

Statistical analysis of data-list with recurring x-values

I have a list of data as follows with repeated x-values: ...
3
votes
1answer
211 views

Replace elements in a list

Suppose that I have a list: ...
2
votes
0answers
203 views

Derivatives of list elements

Could someone explain the odd behavior of the Derivative function when drawing arguments from lists? We have, ...
2
votes
2answers
801 views

Importing several huge files with headers & footers

having here several files in ASCII format http://ge.tt/91rv0Jf/v/0 I want to import, while removing headers and footers and then join the several lists. ...
5
votes
4answers
411 views

Any rule of thumb for converting a simple mathematical expression into a pure function?

By simple mathematical expression I mean one with a few functions and few variables copied into MMA in a mechanical way from a math book. For example this one, giving the distance between two points ...
1
vote
1answer
129 views

Splitting list of sums into a sum of lists

I want to split a list of sums into a sum of lists For example, I'd like to turn {{x + y + z}, {x}, {y}, {z}} into ...
5
votes
1answer
222 views

Is there an equivalent of “shiftdim” of MATLAB?

Recently I'm spending my time implementing some computer vision algorithms, which usually handle a large amount of data. The problem I'm facing now is that I have to reform my video data to pass it ...
6
votes
3answers
522 views

Replace “,” in a list with “.”

I have a list which consists of numbers which use comma (,) instead of dot (.) as their decimal point. I would like to replace the commas, but only those commas which are followed by more than five ...