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.

learn more… | top users | synonyms

8
votes
2answers
255 views

Manipulating OptionsPatterns[]

How do you combine OptionsPatterns? For example, I would like to have a function that can take both options that I specify, and options for all graphs: ...
18
votes
3answers
352 views

Nested definition: How can I define a function with a passed-in expression?

Here's a simplified version of what I'm trying to do: ...
22
votes
6answers
1k views

Convert an expression to a Function

I need a function which can take an expression and return a pure function based on the symbols in the expression. The symbols might have values so must be protected from evaluation. It is probably ...
3
votes
9answers
1k views

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

I'm trying to solve the fourth Project Euler's problem with this: ...
4
votes
2answers
162 views

Standardizing a coset table via matrix manipulation

Suppose we have a group $G$ and a subgroup $H$. A coset table encodes the permutation representation of $G$ on the right cosets of $H$. When we want to use these coset tables in calculations, it is ...
5
votes
4answers
582 views

Swap two entries in a matrix

Is there a nice, simple script one can use to swap two entires in a matrix? For example, suppose we have the matrix below: $A=\begin{pmatrix}2 & 4 & 1\\ 3 & 1 & 2\\ 4 & 3 & 1 ...
3
votes
2answers
356 views

Defining a function using Series? [duplicate]

Possible Duplicate: General::ivar is not a valid variable when plotting - what actually causes this and how to avoid it? I need to define a function using the output of series, i.e. ...
4
votes
1answer
175 views

Finding mappings between expressions

Suppose we have an expression of the form: $j=\frac{A\left(t\right)}{B\left(t\right)}=\frac{C\left(s\right)}{D\left(s\right)}$ That is, $j$ can be expressed either as a function of $t$, or as a ...
11
votes
1answer
417 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 ...
3
votes
1answer
193 views

Evaluation of self-defined functions

I defined a function that I call disc which I want to minimize later. The function is defined as ...
11
votes
4answers
442 views

Assessing argument type in set delayed function definitions

I'm wondering how to properly assess the type of arguments passed to functions defined with :=. I want my functions to be the most efficient, unambiguous and clear ...
10
votes
2answers
434 views

Proper way to add vertices to an adjacency matrix

I'm looking for a robust way to add vertices to a graph by modifying its AdjacencyMatrix. Here's what I have so far: ...
2
votes
3answers
2k views

Passing a matrix as a function argument

I am trying to do the following: ...
3
votes
3answers
156 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 ...
2
votes
2answers
198 views

Working around behaviour of EdgeRenderingFunction

One can make graphs GraphPlot[{1 -> 2, 2 -> 3, 3 -> 4, 4 -> 5, 5 -> 1, 1 -> 1, 5 -> 5}] and one can generalize the input such that one ...
2
votes
3answers
227 views

How to Compute Aggregate Best and Worst Cases for a Large Number of Estimates?

I need to aggregate multiple estimations, but I haven't been able to find a built-in function in Mathematica that aggregates multiple probablity estimations (I am specially interested in estimations ...
4
votes
2answers
2k 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 ...
16
votes
2answers
781 views

Define parameterized function

I would like to be able to define the gain function of a system from its parameters. Specifically, I'd like to define a function that accepts two inputs, call them $b$ and $w$, and returns a function ...
17
votes
3answers
745 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: ...
4
votes
2answers
261 views

Returning Replacement Rules in a function and using it later on

I would like a function which returns replacement rules as some internal mathematica functions are doing and use the results in other functions. I could not find any information on that and I'm ...
6
votes
2answers
345 views

Passing unquoted strings (poor man's enumeration)

I would like to be able to pass an unquoted string as a parameter to a Mathematica function [that I am writing] and have it show up without evaluation if the string happens to be defined. Thus I would ...
2
votes
3answers
203 views

Ways to change an explicit function into a pure function

I'm trying to use FixedPoint to solve a transcendental equations, but the first argument of the FixedPoint should be a pure ...
16
votes
3answers
548 views

Function that counts the number of arguments of other functions

I have a newbie question: is it possible to write a function that counts the arguments (total and optionals) of a given function? Possibly it should be able to work with built-in and custom functions ...
16
votes
5answers
2k views

The difference between 0. and 0

I have a function for which 0 is a special case: f[A___, 0, B___] := 0 But since I am doing numerics, sometimes in the course ...
2
votes
2answers
120 views

How to evaluate this product

I was trying to evaluate this product $$ \sin (1^\circ) \sin (2^\circ) \sin (3^\circ) ... \sin (88^\circ) \sin (89^\circ) \sin (90^\circ) $$ But I think it got weird results with this ...
10
votes
2answers
887 views

Converting ConditionalExpression to Piecewise

I have Solve[] return a list like ...
35
votes
3answers
1k 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 $0$s for blank space and $1$s for filled spaces ...
9
votes
6answers
2k views

Recursive function with if-statement

I am trying to represent the following function definition in Mathematica: $$\begin{align*} f(1)&=1 \\ f(2n)&= \begin{cases}f(n) & \text{if}\space n\equiv0\pmod{2} \\ 2f(n) & ...
16
votes
9answers
957 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 ...
20
votes
4answers
679 views

Can a function be made to accept a variable amount of inputs?

I have a function that takes two inputs and processes them for a single output. What I need is one that can take a varying number of inputs. and process them to a single output. Is this possible in ...
2
votes
2answers
149 views

Is it possible to use PropertyValue to modify properties of Graph objects in a list?

This post can be seen as a follow up to Property assignment on a graph vertex using PropertyValue does not work inside a function. I have defined a function: ...
5
votes
1answer
646 views

Nesting multiple functions of multiple variables

I was wondering how one would go about nesting multiple functions of, say, two variables. The problem comes from trying to implement the Chirikov standard map without using "for" cycles. I found a ...
23
votes
1answer
496 views

How to augment the realm of functions Mathematica thinks it knows how to integrate symbolically

My question involves extending the functionality of Integrate over specific integrals in the most generic manner. Specifically, is it possible to "hack into" ...
0
votes
2answers
193 views

Constraining two points, a specified distance apart, to a line

Suppose that I have two points in the xy plane: pt1 and pt2init. pt1 is fixed in space, ...
26
votes
4answers
595 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 ...
6
votes
1answer
137 views

Property assignment on a graph vertex using PropertyValue does not work inside a function

I created this function: AddStone[board_Graph, v_, s : white | black | empty] := PropertyValue[{board, v}, VertexState] = s This function should change the ...
14
votes
3answers
238 views

What's wrong with this pattern of the form Except[Repeated[…]]?

I'm trying to build a head that recognizes molecules. Here's the code ...
13
votes
3answers
456 views

Is it possible to get the order of inputs when “overloading” an orderless function?

When working with symbolic matrix operations or other objects which don't have commutative multiplication, it would be nice to not have to constantly switch out times for ...
7
votes
1answer
732 views

How to find the smallest root

I have a continuous, differentiable, monotonic, bounded function called F[t]. If t -> Infinity then ...
6
votes
3answers
311 views

Using function with multiple definitions in Manipulate

I'm trying to use Manipulate to visually try out different values of lambda in a Box-Cox transformation. I've created a boxcox ...
4
votes
3answers
170 views

Constructing a function with Flat and OneIdentity attribute with the property that otimes[a]:>a

I want to have a function (called otimes) with the following two properties: it has the attribute OneIdentity and ...
15
votes
1answer
666 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 ...
7
votes
3answers
204 views

Generating date ranges

How can I, in one line, generate all the dates with a constant day difference from one date to another? For example, if I'm interested in dates in the interval staring from 24.4.2012 till 2015 and a ...
11
votes
2answers
600 views

How to plot a barycentric line

I want to plot a barycentric function on an equilateral triangle (ternary plot). For example f1 = {Abs[Sin[x]], Mod[x, 2], Abs[Cos[x]]}; At the moment I evaluate ...
14
votes
5answers
800 views

Picking random items out of a list only once

I'm trying to create a function that randomly returns a value from a list but remembers the values that have been given before. At the end when the list is empty it should return an empty list. ...
7
votes
4answers
1k views

Force function to make assumptions about its input variables in Mathematica

I'm trying to force a Mathematica function to make an assumption about its input variables. In my case, I'm trying to define a function to return the pdf of a Gaussian. But let's use a simple toy ...
4
votes
1answer
226 views
4
votes
1answer
259 views

How do I use the result of Solve in a function definition?

I'm trying to adapt the following piece to the part where PowerF is a function of amax. ...
14
votes
2answers
374 views

Using several anonymous functions mixed together

This works: list // BarChart[#[[2]], ChartLabels -> DateString @@@ #[[1]], ChartStyle -> "Pastel"] & This doesn't: ...
4
votes
3answers
515 views

Integrating with multiple indicator functions

I am trying to calculate an integral involving multiple indicator functions, such as: $$ h(u,v,w) = -\int_0^1 J^{\prime\prime}(s) (I_{(0,s]}(u) - s)(I_{(0,s]}(v) - s)(I_{(0,s]}(w) - s)\, ...