Tagged Questions
5
votes
3answers
93 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 ...
5
votes
4answers
220 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 ...
11
votes
1answer
127 views
How can I make threading more flexible?
Threading automatically with Listable functions requires the argument expressions to have the same length (or for one of them to be atomic). For nested lists the ...
8
votes
4answers
134 views
How to pass a list of arguments into HoldAll
I have a list of arguments (which in reality is lengthy):
arguments = {a, b, c}
arguments2 = {a_, b_, c_}
f[Sequence@@arguments2] := a + b + c
Note: It seems ...
4
votes
2answers
92 views
How to only work on sublists with non-zero (or positive) values
i have a large compositional dataset which contains non-zero and zero values. here is a sample:
...
10
votes
3answers
376 views
What is Mathematica's equivalent to MATLAB's filter function?
The MATLAB code
filter(0.5,[1, -0.5], [1:10])
is equivalent to
Rest@FoldList[(#1 + #2)/2. &, 0, Range[10]]
I don't ...
1
vote
1answer
105 views
Creating an array eval [closed]
How can I create an one dimensional array (a vector) evaluating a function of two variables? I know how to do it with one variable:
Array[f, n, {a, b}] generates a ...
1
vote
1answer
76 views
How do I define a function that, when given a list of parameters, plots a family of functions?
So far I've got this:
draw[a_, b_] := Plot[{f[a, b[[1]], x], f[a, b[[2]], x]}, {x, 0, 5}]
The function draw will be used like ...
4
votes
6answers
172 views
Filter list with different list in it
I have a list like:
{{{4, 14}, 1}, {{4, 15}, 1}, {{4, 16}, 1}, {{4, 17}, 1},
{{4, 18}, 1}, {{4, 14}, 3}, {4,15}, {{4, 16}, 2},{4,18}}
Now I want to ...
1
vote
3answers
246 views
Generating pairs of additive and multiplicative factors for integers
Given an integer $n$, I want two lists:
a) the set of pairs of the divsors $a,b$ into exactly two factors $n=a\cdot b$,
b) the set of pairs $a,b$ of two summands $n=a+b$.
The code I came up ...
2
votes
0answers
194 views
Generating a function which outputs possible chemical reactions
I want to make a list of chemical reactions and I write them down in a $\require{mhchem}\LaTeX$ format. They are of the following form
$$NA_n^i+MB_m^j \rightarrow \hat NA_{\hat n}^{\hat i}+\hat ...
6
votes
2answers
309 views
Building matrices by attaching vectors (columns) and matrices
Having the need to attach a column to a matrix or to join matrices to make longer rows is an operation that I use very frequently and I find the Join function ideal ...
1
vote
0answers
76 views
Non Commutative Multiply [duplicate]
Possible Duplicate:
Non-commutative symbolic linear algebra
I want to multiply two matrices, for example,
A = {{e, f}, {g, h}}
B = {{a, b}, {c, d}}
...
3
votes
3answers
165 views
How to pull scalars out of a function that should act on lists?
Suppose I have
A = a vecA
B = b vecB
where a and b are supposed to be arbitrary scalars ...
2
votes
1answer
75 views
Specifying form in MemberQ
This seems like a very simple question, the answer to which should be obvious to me. So I won't be offended if this question is closed. But I'm having trouble figuring out the answer.
I would ...
2
votes
2answers
131 views
Constraining a random function
This question is a follow-up from here. I have a function that generates a list of correlations between some random variables:
...
2
votes
3answers
116 views
Function[] argument nesting for operations like Select[]
The following code selects a special element from a list
thelist = {"this", "notthis"};
Select[thelist, (# == "this") &]
What I want is a function which ...
14
votes
3answers
343 views
Using pure functions in Table
I need a table with the elements made of pure functions and list elements. This is a simplified example:
I need a list as:
...
28
votes
2answers
590 views
Tiling a square
I wondered if there was a way to automate the process of finding a way to tile a tile into a square.
The idea is to represent the tile with a matrix of 0s for blank space and 1s for filled spaces ...
15
votes
8answers
536 views
How do you check if there are any equal arguments(even sublist) in a list?
I would like to set up a function which has to return True if at least two arguments of a given List are equal.
So if I give {1,4,6,2} to the function it has to ...
8
votes
3answers
158 views
How to make MapAt work with Span?
Span (;;) is very useful, but doesn't work with a lot of functions. Given the following input
...
4
votes
1answer
182 views
4
votes
1answer
166 views
What's the most intelligent way to store the information of a selfmade graph?
I have a very long list of element, say $a1,a2, a3$,..., and they are all connected in that each is the child of many parents. E.g. $a74$ is associated with $a2,a55,a71$, and also contains ...
