Tagged Questions

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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2
votes
1answer
158 views

Why does the first derivative of a piecewise continuous function turns out with discontinuities?

I have this piecewise continuous function which is also continuously differentiable over time : ...
15
votes
4answers
240 views

Enforcing correct variable bindings and avoiding renamings for conflicting variables in nested scoping constructs

Using global variables the following turns an "expression" into a Function: expr = 2 x; Function[x, Evaluate[expr]] Of course ...
5
votes
1answer
127 views

How to find the name of the current function

I would like to know the name of the current function from within that function. For example, consider the following code ...
1
vote
0answers
73 views

How can I obtain the function described by given set of central moments?

I want to investigate how my function P behaves with different probability functions rho as input variables. This means ...
10
votes
1answer
288 views

Lazy lists of Tuples and Subsets

I'm trying to build a lazy list that evaluates the n'th m-tuple or subset of a given list using Mathematicas ordering without calculating all the Tuples. The purpose is to allow for example the ...
2
votes
4answers
279 views

How to write a differential operator in Mathematica

I have a very basic question. I am trying to code the LHS of the differential equation: ...
1
vote
1answer
102 views

Function definition and delayed assignment

I need to define the following function MyWavelet[n_]["PrimalLowpass", prec_ : MachinePrecision] := Table[(-1)^(j - 1) h[[2*n - j]], {j, 0, 2*n - 1}] which ...
4
votes
4answers
204 views

Differentiating space curves

I'm trying to do some very basic differential geometry of space curves. For example, a space curve $\gamma:\mathbb R\to\mathbb R^3$ has unit tangent and normal vectors given by ...
3
votes
1answer
78 views

Using NestWhileList to determine smallest prime value in series

I have a function recursively defined as follows: $a_{n+1}-1=(a_n-1)\times lpf(a_n)$, whe $lpf(x)$ is the least prime factor of $x$. Now, given an initial value of $a_0$, I would like to find the ...
48
votes
4answers
2k 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 ...
4
votes
1answer
111 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: ...
4
votes
3answers
96 views

Creating a nonperiodic function in mathematica

I want to create a non-periodic square wave with values of 1 and -1(not necessarily alternating). For e.g. I want to convert an arbitrary array like {1,-1,-1,1,-1,1,-1} into a function. I tried ...
1
vote
1answer
66 views

Confirming the existence of a function related to a matrix

Is it possible to get an answer to the following question in Mathematica? Let $M$ be a $n$ by $n$ matrix, is there a function $m:\mathbb{N}\times \mathbb{N}\rightarrow \mathbb{Z}$ such that ...
0
votes
1answer
80 views

How could we define a function recursively?

Let us first consider the constructon of the following simple iteration ...
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 ...
3
votes
1answer
112 views

Downvalues vs. Scoping for Functions

Regarding my recent question on using a default value for a function argument when a pattern was not met yielded some interesting answers, but the general consensus was "Yes this can be done, but ...
0
votes
1answer
163 views

How do I make function A create and return function B?

My basic need is I have to take lots of data and other information and assemble it into a function (static parameters). I then need to call the function many times for numerical results for many ...
6
votes
4answers
171 views

Function argument to default under certain condition

Inspired by this and this question (and how I handle this in practice), what is the best way to default a function value when a certain condition is met? For example, if a function is defined as: ...
2
votes
2answers
112 views

How to achieve Set+Part like behaviour in custom Set function?

So I've been toiling away on my DataFrame package. I've been trying to get Set to work with it, but it seems it either can't be done (ie via ...
10
votes
1answer
109 views

Multiple templates for a single user-defined function

How do I use the ::usage tag to allow the Mathematica v9 front end to know that there are multiple ways to call an overloaded function (a function that can have ...
3
votes
1answer
87 views

Is it safe to assign a variable and function of the same name for different things?

I'm writing out a notebook that goes through the van der Waals Equation of State for gases, and I run into a situation where I want to assign (simplified) Tc[b_]:=5b, use that to solve for b in terms ...
10
votes
0answers
127 views

func::usage needs to be run twice?

There is an annoying problem that I can't figure out why it's happening. I have defined a usage for a my function tensorA: ...
3
votes
2answers
206 views

Ways to plot interpolating functions more economically?

I am interpolating a lot of data over geographic coordinates obtained via GPS, and frequently I need to plot these interpolated functions together. For example, I may have an interpolated elevation ...
2
votes
1answer
104 views

Can my permutations function be defined using iteration?

I have two functions, tuples and perm. They are similar. ...
3
votes
2answers
109 views

Apply UpValues before Listability

I'm trying to modify Plus but am running into trouble with it being Listable: ...
2
votes
9answers
927 views

How to find palindromic numbers (Project Euler #4)?

I'm trying to solve the fourth Project Euler's problem with this: ...
1
vote
1answer
134 views

Fitting parameters of user defined function returning discrete values

So, I'm fairly new to Mathematica (apologies in advance for the noobiness), and I'm having some problems regarding fitting the parameters of a user defined function to data. I'll give a representative ...
3
votes
1answer
67 views

Values set using SetOptions are staying in the kernel, beyond the necessary time [closed]

I wrote a function name as functionTest and also mentioned default Options. ...
10
votes
2answers
199 views

Functions that remember their values

Can someone explain what is going on with the following ... func[y_] := func[y] = (Print["Hello world !!!"];) func[1] Hello world !!! ...
0
votes
1answer
134 views

How to write case, in piecewise function, correctly [closed]

I want to plot graph of this piecewise function in Methematica: $f: [0, 1] \mapsto \mathbb{R} $ $f(x)= \begin{cases} \frac{1}{x - \frac{1}{3} } & \text{ if } x \in [0, \frac{1}{3}> \newline ...
3
votes
0answers
43 views

How to influence Suggestion Bar in your package/code [duplicate]

Possible Duplicate: Is it possible to customize the Suggestions Bar? I have written a little code (like a minipackage) of different functions. In using my code, the user typically starts ...
0
votes
1answer
103 views

Creating Recursive Sequences

Quite a simple question, I reckon, however, even quite an extensive search hasn't helped me. I want to define a recursively defined sequence that starts with defined ...
3
votes
1answer
124 views

Feedback on my Subscript code

I have written a code, and I need a little feed back.. I want to make the Subscript distributive across (1) addition and (2) multiplication to mimic short-hand for ...
1
vote
3answers
145 views

More than one expression in the Table[] command?

I would like to construct a Matrix using the Table[] command. The issue is that I would like to use more than one expression for it. What I need to obtain is something like this : ...
2
votes
2answers
103 views

Hiding certain user-defined functions in front-end autocompletion

I have written an elaborate code that contains a collection of functions for the user and a bunch of auxiliary functions whose existence I would like to hide away from the user. I've written my code ...
7
votes
7answers
494 views

Can my color function be written more simply?

The code shown below works well, but I think the pure function I'm supplying to the ColorFunction option could be more elegant. How can I simplify it? ...
4
votes
2answers
153 views

Pattern matching repeated structures with named subexpression components

I am trying to write a function with a pattern that tests its arguments for a particular structure. But in that pattern I'd like to name a subpattern to make it easier to exract and operate on. The ...
2
votes
2answers
301 views

Creating custom functions with multiple arguments

I am hoping that this isn't a stupid question so feel free to vote it for closure. Google failed somehow. I want to define a custom function (more complicated than the usual ...
0
votes
0answers
52 views

Enable syntax-coloring on user-defined function [duplicate]

Possible Duplicate: Syntax highlighting for your own functions I have defined a function myIntegrate that carries out a routine similar to Mathematica's ...
3
votes
1answer
107 views

Permuting indices to form fully symmetric tensor with repeated indices

I have written a function (version 8) that takes as an input a list of indices such as {i,j,k} and outputs a fully symmetric tensor function containing $p_i$ and ...
3
votes
3answers
98 views

How to identify patterns in a tensor-polynomial and replace appropriate symbol?

I want to write a function tensorReplace[input] that takes a tensor polynomial in $r_i$ such as $r_i r_j r_k+r_i q_j q_k +q_i q_j q_k$ , and replaces each monomial ...
2
votes
1answer
114 views

Rookie mistake in defining a function with Modules?

I can't figure out what's wrong with this piece of code. I'm trying to define a function that counts the occurrences of x, y and ...
2
votes
3answers
234 views

How do I construct a pure function to extract data fields from records that are strings?

How can I get from data segment format to the final segment format with a pure function? The data fields are fixed length. There are no separators between the fields. a) list ...
7
votes
4answers
289 views

Is there a concise form of Which or similar conditional?

Suppose that I want to write a function fun that takes an Integer num as input, and returns ...
9
votes
1answer
337 views

How to Combine Pattern Constraints and Default Values for Function Arguments

EDIT: As several respondents have noted in the answers and comments below, the original example had a default value that would never be used because of the way patterns and default values are ...
-4
votes
2answers
148 views

How to correctly call a Module within another Module?

How to embed and call the correct embedded modules inside another Module? Say: ...
7
votes
3answers
133 views

How to set a TraditionalForm output for a symbol

How do I set a TraditionalForm output for a particular symbol/function? In particular I would like my user-defined symbol ...
1
vote
3answers
160 views

Variables Inside Functions Not Evaluating

x = 5*y function1[y_] := x function1[5] Am I wrong in thinking that function1[5] should equal 25? Instead this comes out. ...

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