For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.

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0answers
31 views

How to use OptionValue inside a pure function [duplicate]

I want to define a function with OptionsPattern as argument which returns a pure function using OptionValue: ...
1
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0answers
70 views

Build basic Adobe Kuler-type construction: improving performance / speed

Adobe Kuler is a useful web tool to create colour palettes, but it is limited to 5 colours. I am trying to make a basic Kuler-type construction, but it is very slow, and crashes on my computer for > ...
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0answers
34 views

How to make FindMiniumum work with delayed function and NIntegrate [duplicate]

I can plot my function penalty[v] just fine, but FindMinimum doesn't work, it just complains non-numerical values from ...
2
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2answers
166 views

How to get `Series` to recognize user-defined function has pole

Edit for clarity: How does Mathematica's function Series know that Gamma[x] has a pole at ...
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0answers
40 views

Symmetrize a function

I am working with a function in several variables. I need a function which symmetrizes it. Namely in case of two variables it is f[x, y]+f[y, x]. For three variables it is $$f[x , y , z] + f[x, z, y] ...
0
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1answer
35 views

How to turn a function's input argument into a new function

I want to write a function via a module that takes a user's input and creates a function from the input within the module. That is something like Input: ...
80
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4answers
5k views

Functions with Options

Suppose you want to create a function which has optional arguments. Maeder's book Programming in Mathematica covers the topic extensively up to version 3, but some things have changed/evolved since ...
3
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1answer
75 views

Implementing the Cimmino method [closed]

What am I doing wrong? I am trying to implement the Cimmino method, an iterative method for the solution of linear algebraic systems. The final output should be a vector. Here is a description of the ...
6
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4answers
110 views

Multiple output cells, suppressed by semicolon

I'd like to write a function that outputs multiple cells, as in Multiple output cells, but not when the function is called with a semicolon at the end. Any idea how?
-2
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1answer
44 views

Calculate column number from alphabetic column reference in Excel [duplicate]

Here's a fun brain teaser. Can you give me a mathematical equation to calculate the column number of a Microsoft Excel column, given the alphabetic column reference? Let X, Y, & Z represent the ...
3
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2answers
61 views

Catch parameter order and error using functional form

Question: Why does this fail? In:= (Catch[#] &)[Throw[17]] ...
2
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0answers
61 views

Lyapunov Exponent as a function of parameter

I am working at Rossler system and I would like to ask you for some help. This system is described by equations: \begin{array}{ll} \dot{x} = -y - z \\ \dot{y} = x + 0.2y \\ \label{eq:UkladRosSP} \dot{...
4
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1answer
113 views

How to use the built-in function GraphElementData

Very surprise to me.I found this is a built-in function but it is undocumented.Such as this answer's "CurvedArc" and "Curvature",...
3
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1answer
468 views

Gâteaux (directional) derivatives and higher order differentials of a functional

I would like to calculate the Gâteaux derivative of a functional (i.e. a function depending on functions). A simple example for the Dirichlet functional: $L(u(x))=\int_0^1 \frac{1}{2} (u'(x))^2 dx$ ...
6
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1answer
121 views

Filters on image vs data

I was using GaussianFilter and realized that applying it to an array yields a different result from applying it to an image. For instance: ...
41
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5answers
1k views

Why is there no PositionFunction in Mathematica?

Too often I have seen the programs of inexperienced users greatly slowed by using Position in an iterative fashion, when far faster would have been to compute a ...
3
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0answers
63 views

How to build a ColorFunction that can take a non-numeric value? Blend returns an error

I'm trying to use an external package, defined here. This package has a private function called makeColorFunction that essentially works by taking an input color ...
-5
votes
1answer
58 views

What is this function aimed to do? [closed]

Table[Sum[tmatrix[[i, j]], {i, 1, 2}], {j, 1, 2}] apparently creates some sort of a table, and it evidently works on a matrix....although it is hard for me to understand what should it do beyond ...
8
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1answer
188 views

How to efficiently write code with many functions that have variable number of iterators/arguments/

I am finding myself having to code functions like this: $$\text{answer} = \sum_{k_0 = 0}^{\color{Blue}n_0} \sum_{k_1=0}^{\color{Blue}n_1}\cdots\sum_{k_{N-1}=0}^{\color{Blue}n_{N-1}} \frac{P_{k_0,k_1,\...
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1answer
57 views
10
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1answer
1k views

How does a Pringle lose its curvature?

Nom! As part of a bigger project, I've was writing some code to calculate the scalar curvature of surfaces of the form $z = f(x,y)$. This uses a general calculation of the scalar curvature to produce ...
1
vote
2answers
125 views

Function does not execute commands and fails to evaluate [closed]

The code I am trying to execute: hh[x_, y_] := x + y; hh[{3, 4}] The expected output: 7 However, on output I get ...
1
vote
1answer
80 views

Remove part within square brackets for function

So I've defined a variable as follows: q = {{x[t]}, {Φ[t]}} V=0.5*x[t]^2*m^2+0.5*Φ[t]^2*I I've had to differentiate with respect to time so: ...
8
votes
2answers
111 views

Why a function returns two different values if copied into a Notebook or imported with Get from a Wolfram Mathematica Package?

I have some Mathematica code that shows a behaviour I really cannot understand. The code only contains a bunch of function definitions. If I paste it in the Notebook Front End and I evaluate it, I ...
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0answers
53 views

What I make wrong with Module command;

I have a differential equations that I have to solve in two parts.e.g: ...
1
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1answer
56 views

Derivative in my package return 0

I'm writing my package (.m) in Mathematica and when I'll call the function returns 0 instead of right output. Here's my code: Package.m ...
1
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1answer
73 views

How to use recursion to find a logical dual

I want to make a little function that goes through a propositional formula and gives it's dual. Here is what I currently have: ...
0
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0answers
43 views

Greatest common denominator command. Can you explain why this command works?

Can you explain how this function works? mysteryFunction := Fold[#/#2 /. {n_~_~_ -> #/n, _ -> #2} &, #, {##}] &
7
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2answers
4k views

Module with “local functions”

I am trying to use a Module having "local functions", i.e., those which I need to define only inside this module. So I tried this: ...
3
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0answers
60 views

Custom units Compatible with Conversions [closed]

I am writing a Mathematica Palette to work with units, and am wondering if anyone knows a way to define new units outside of the standard ones that come with Mathematica 9. I do know of the ...
5
votes
2answers
280 views

Simpler way to type Derivative[1, 0][u][0, x]

Though not unbearable, I always feel a little nervous when typing partial derivatives at a specified place e.g. $u^{(1,0)}(0,x)$, which happens a lot when setting initial/boundary conditions for PDEs. ...
0
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0answers
37 views

How to define a general linear function [duplicate]

I'm trying to work with a general linear function in Mathematica. I would like to assign some sort of rules to a function, say Tbar, to evaluate linearly. Basically what I would like to do is have ...
1
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0answers
39 views

Getting a list of function definition parameter values [closed]

If I define a function over certain values: f[0] = 1 f[1] = 2 f[2] = 3 How do I get the list of parameter values that it's been defined on? ...
2
votes
1answer
128 views

Syntax f[x_][y_]

Need to understand the principle of the distinction between f[x_,y_] and f[x_][y_] It seems also that z[x_, y_][a_, b_, c_][α_, β_] := a (x + y)^b + c/(α-β) ...
1
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0answers
62 views

Distinguish hashtag # operator when using multiple functions [duplicate]

I would like to do this list = Append[list[[#]],Map[list2[[1, #]] & , list[[#, 4]], {2}]] & /@ Range[Length[list]]; But I would like to substitute ...
1
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1answer
63 views
21
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1answer
494 views

How can I export my learned ClassiferFunction[] and PredictorFunction[]s?

Mathematica 10 provides beautiful high-level machine learning functionality. Sadly, the learned functions once created are rather opaque objects. I need to use them in other projects, so here is my ...
21
votes
7answers
1k views

Using patterns in pure functions

Pure functions may be handy if you don't want to assign your function a name. For example I would calculate $x(x-1)$ for some numbers $x$ by ...
10
votes
1answer
195 views

How to construct the RHS of Wick's theorem

I've been trying this for a few days now, but I just can't seem to find an efficient (speed-wise) functional way to code the following task. Context: I would like to construct an expressions that is ...
6
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1answer
38 views

How is Attributes protected and yet can still be set?

The Attributes function itself has the attributes: Attributes[Attributes] ...
9
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6answers
477 views

How to generate this structure of a list without `While` and the like?

I need to create a list that holds, for given integer d, the elements $1,\ldots,d,d+2,\ldots,2d,2d+3,\ldots,3d,3d+4,\ldots,d^2$ where $\ldots$ is just denoting ...
5
votes
3answers
181 views

Number by permutation

I want a function that compute number of permutation in lexicographical order. E.g. ...
2
votes
1answer
172 views

Passing function as argument

I've been mucking around with passing functions as arguments to other functions and via trial and error seem to have something that works. I was wondering if someone could have a quick look at some ...
1
vote
1answer
38 views

Plot is empty (probably) due to poor function definition

I am trying to plot my response $x(t)$ as a function of system parameter $M_0$. Here is my code to regenerate my problem ...
1
vote
2answers
107 views

n fold convolution of a function via a recursion function

I wanted to write a recursion function to calculate the n-th convolution of a function f[x_]. I wrote the function ...
7
votes
2answers
169 views

Sets and sums of different elements

Consider the set S={w,x,y,z}. If the set of all possible sums of any three different elements from S is {-1,3,5,8}, then what is the set S? How could I solve this function using Mathematica?
8
votes
2answers
98 views

For loop works at top-level but not in a function

Why does this work: For[i = 1, i <= Dimensions[list][[1]], i++, list = Insert[list, i, {i, 3}]] But this doesn't: ...
5
votes
1answer
78 views

How to obtain the Derivative of a pure Function of variable number of arguments?

Here is a function f that takes a variable number of arguments: f = Times[##]*Log[1 - Times[##]] & I now want to ...
0
votes
1answer
92 views

How to turn a subroutine into a function?

I've written a subroutine that takes in 6 matrices and after some manipulation returns back 3 new ones. I will use this subroutine fairly often in this notebook so I think it would be easier to turn ...
4
votes
1answer
104 views

How do I localize an assignment to expression (instead of symbol) within scoping construct?

Is it possible to localize an assignment to an expression (defined via UpSet) instead of a Symbol within a scoping construct? ...