Questions on the manipulation of List objects in Mathematica, and the functions used for these manipulations.
1
vote
1answer
95 views
2
votes
2answers
70 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
67 views
Format Preservation of FullSimplify on Indexed System of Autonomous Equations
I currently have a large system of 150 autonomous differential equations. I've indexed a more managable dummy system of identical form, using Part to reference ...
13
votes
1answer
126 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
58 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
53 views
3
votes
3answers
119 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
62 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
127 views
3
votes
1answer
112 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
75 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:
...
2
votes
2answers
83 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 ...
2
votes
1answer
89 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 ...
2
votes
1answer
101 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
120 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
196 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.
...
-6
votes
0answers
110 views
Extracting points data from a 3D curve surface?
I have a 3D data set, and I have used it to create a 3D plot, but some of the data points are errors and need to be removed. How I can I remove the bad points from the plot?
...
2
votes
1answer
72 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
214 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
146 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
91 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
34 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,
...
0
votes
0answers
58 views
Problems with ListDensityPlot
I have the errors in one quantity $x$ in a List form as $(\Delta x,z)$, being $\Delta x$ the error and $z$ the value in which $x$ has the respective error. I want to make a density plot of the errors ...
2
votes
2answers
97 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
0answers
87 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
106 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
181 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
151 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 ...
0
votes
0answers
63 views
6
votes
1answer
94 views
How does `LongestCommonSubsequence` work?
When I recently came across this posting about LongestCommonSubsequence I was curious about how the function worked.
...
3
votes
2answers
133 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 ...
1
vote
3answers
124 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 ...
7
votes
5answers
326 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
113 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
83 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
77 views
Picking certain pairs according to a condition
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
82 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
129 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
124 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)
...
2
votes
1answer
101 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
136 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
70 views
13
votes
5answers
314 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
73 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
96 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
67 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
104 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
80 views
2
votes
0answers
100 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
122 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.
...
