Questions tagged [argument-patterns]

Questions concerning argument patterns used as formal arguments in function definitions (e.g., := expressions) to restrict the kinds of values that can be passed as actual arguments. Also questions about how such patterns can be used to achieve function overloading.

Filter by
Sorted by
Tagged with
6
votes
0answers
56 views

Why does Longest not work on OptionsPattern?

When having a function with optional arguments and options, I frequently find myself writing something like this: ...
6
votes
1answer
187 views

How to check the number of function arguments given by the user

Suppose I have defined the following function inside a package that can take 2 arguments. f[x_,y_]:={x,y} So, if the user gives ...
0
votes
1answer
33 views

Restrict the domain of a function (and plot) it) when it depends on the value of a parameter

I know similar questions have been asked, but I am very new at Mathematica and other questions/answers are quite complex and do not suit the code I want to write. I want to restrict the domain of the ...
2
votes
1answer
22 views

Refer to argument in condition for other argument

The condition for b here doesn't recognize a. How can I fix this? ...
0
votes
0answers
54 views

How to convert Symbol to Number?

Question I have a variable x which is associated with the number 1 : x= 1 In the program, I faced with the data type problem ...
1
vote
2answers
90 views

Unusual performance of the Cases function [closed]

Recently I was surprised by unusual performance of Cases function. The code ...
2
votes
0answers
58 views

How does Mathematica choose which function definition to use?

I was wondering what the process of matching function arguments arguments against different function definitions actually looks like for Mathematica. (Just to be clear, I'm not simply looking for an ...
6
votes
0answers
92 views

Exceeding recursion limit with no obvious recursion: Optional pattern-matching causing nonlocal behavior

So, I've come across something strange, and wanted to get a deeper understanding of what was going on. Consider the following code: ...
2
votes
1answer
71 views

Function of function with arbitrary number of arguments

Given the function (simplified example) g[En_, k1_] := En^2 *k1 I have to plug it inside another expression, where En is ...
0
votes
1answer
65 views

Using conditions to construct a function [closed]

This is the hint my professor provided. We have 6 separate cases to define the function pow[x_ , r_]. The first case is where ...
4
votes
1answer
93 views

Force results to be displayed in a way often seen in traditional math [closed]

I want to get my output in the form that I would write by hand. I have tried with TraditionalForm, but it did not work. I've looked at several answers in this SE ...
6
votes
0answers
105 views

Difference between the infinite rewriting behavior of evaluation and ReplaceRepeated

In the documentation tutorial/Evaluation it's said that: Every time the expression changes, the Wolfram Language effectively starts the evaluation sequence over ...
0
votes
1answer
73 views

passing splice instructions

Consider some passing splice instructions using start,stop,step pattern ...
1
vote
3answers
75 views

My rule does not do anything (understandably)

I want a rule that would transform, for example, And[i,F[j,k],l,G[m,F[j,k],n],p] into And[i,F[j,k],l,G[m,T,n],p], where ...
0
votes
0answers
18 views

How to memoize with patterns? [duplicate]

Here is an artificial example to explain what I am up to. Define ClearAll[f] f[x_, y_] := f[x, y] = If[x == 0, g[y], g[f[x - 1, y]]] Then ...
0
votes
0answers
49 views

Head of complex sum

We have: 1 + 2 I + 3 + 4 I // Head Complex and 1 + 2 I + 3/5 + 4/5 I // Head Complex But we get: ...
1
vote
0answers
61 views

How conflicting patterns are resolved?

I often find myself doing something like this (probably poor example, sorry) f[x_] := 0 f[x_Plus] := 1 In the back of my mind generally ...
4
votes
1answer
74 views

How to define a parameter with both Optional and PatternTest

Why this doesn't work? k[x_Integer:2?(#>0&)]:=x^2 k[] (*should be 4*) k[2] (*should be 4*) These following are all working as expected: ...
1
vote
2answers
48 views

How to define a function that acts invidually on a varible number of arguments

I am trying to generate a function that applies to each argument for any number and type of arguments. The function might work like this: ...
2
votes
1answer
70 views

Write repeated expressions within a rule more simply

Is it possible to shorten the length of a (delayed) rule (i.e. lhs :> rhs) when there are expressions which repeat several times? Those expressions involve ...
1
vote
0answers
31 views

Is there a way to get the calling information inside the body of a function defined using down value?

Suppose a function has multiple argument structure like follows: ...
3
votes
1answer
232 views

How to use patterns to specify variable type as Boolean (True, False) in analogy to x_Integer, x_Real, x_Complex, x_List, etc

Say I define a function f[x_, y_]:= ..., the concrete definition of which is not important now. What is important though is, that I want ...
3
votes
2answers
67 views

Setting nested optional argument with a default when unpacking from a given Head

I have a head that holds a single argument, and I want to unpack the value inside it while also assigning a symbol to the value itself, for example: ...
1
vote
1answer
32 views

FilterRules works in DateListPlot but not in Plot

I just experience the following problem (this is a MWE just to illustrate). First DateListPlot ...
2
votes
1answer
99 views

Prevent an expression from evaluating a certain way (pattern-matching?)

I've been trying to write some simple code to let me use physics vector notation: $\hat{x}$, $\hat{y}$, $\hat{r}$, and $\hat{\theta}$. ...
2
votes
1answer
70 views

How can I make a function that expects a list of variables behave like a multivariate function? [closed]

I am trying to convert a user defined function that takes two or more variables into a user defined function that takes a list of variables. However, it seems Mathematica treats variables and ...
0
votes
1answer
67 views

How do I define a function that accepts a subscripted variable?

How do I define a function with subscripted variable? I want to write the following expression $\qquad f[a_9] =1+ a_7 + a_9$ I wrote ...
22
votes
7answers
732 views

How to replace all elements of a list by a rule “element” -> “element_”

I have a list: {a, b, c, d, e, f, g, h, i, j} The goal is to get: {a_, b_, c_, d_, e_, f_, g_, h_, i_, j_} I can replace ...
6
votes
2answers
206 views

How to divide list according to the pattern?

There is a list of lists: {{0,0,0}, {0,0,1}, {0,1,0}, {0,1,1}, {1,0,0}, {1,0,1}, {1,1,0}, {1,1,1}} I need to regrup it's elements according to a pattern: "if the ...
0
votes
0answers
54 views

Delayed Rule right-hand-side mis-evaluation

Outline I am trying to create a rule that will give me a minus sign if the number of times A is applied on X is odd where A is some οperator and X a random quantity. Some of the configurations of ...
1
vote
1answer
159 views

Define Function explicitely with List as argument [duplicate]

Background There are multiple ways to define Functions. I would assume all methods are equivalent, and allow for the same options. However, I fail to find the ...
1
vote
1answer
126 views

n derivatives on a function of n variables

I want to derive an expression with respect to each variable of a function $f: \mathbb R^n \rightarrow \mathbb R$. More precisely: $\left(\prod_{i=1}^n\frac{\partial}{\partial_{x_i}}\right) g(f(x_1,...
0
votes
1answer
69 views

How to have NonlinearModelFit not evaluate a function too early?

This is a follow up of my previous question How can I define the following function for arbitray values of the arguments? that received no attention so here I will try to be more concise with the ...
8
votes
3answers
278 views

How can I check if a function can be written as $a * \sin (b * x + c) + d$?

I want to write a function that takes another function, say $f(x)$ and a variable $x$ as input and return True it this function can be written in the form ...
0
votes
1answer
108 views

How can I define the following function for arbitray values of the arguments?

Consider the following function a[m_, l_] = 1/Log[m/l]; with this function I define ...
7
votes
3answers
203 views

changing number of arguments to a function in secondary evaluation

So I have a function that produces answers involving uninstantiated(?) function names, e.g. Out[1]= f[a,b,c,d]. I then want to evalute this leftover result by, ...
2
votes
0answers
85 views

Is there something like a function pattern test?

Is there something like a function pattern test? function[x_?FunctionQ]:=Module[{},] In order that Mathematica can tell if the argument is a function or a ...
1
vote
1answer
68 views

Respecting excluded index in sum

I'm using a function involving a sum where some indices are excluded: ...
3
votes
2answers
153 views

Using DeleteCases with a defined function with two arguments as a pattern

I am trying to manipulate some large datasets in Mathematica. I have plotted the data, and I would like to be able to easily remove points from the dataset, and it's fairly easy to identify the x-...
4
votes
1answer
152 views

A single argument pattern definition applies to multiple-argument patterns?

Consider defining a pattern rule, such as myFun[x_]:=x As far as I understand Mathematica syntax, this rule means ...
2
votes
1answer
42 views

Define different actions for the same operator depending on the nature of its arguments

I am working with terms of the form A**B1**B2 where A, B1, and ...
5
votes
1answer
87 views

Why is { } interpreted as an option in my function? [closed]

I don't understand the output from: ...
1
vote
2answers
100 views

Defining a function that treats input as two unordered lists

I have a function f2 I'd like to code into Mathematica with the property that it takes in two lists, treats those lists as unordered, and maps to a symbolic value. If I were instead using a function ...
6
votes
1answer
126 views

How to use VBA types with UNDERLINE in it's name in NETLink?

When coding with VBA functions in NETLink, I need the enum reference. It's ok to get the ...
3
votes
1answer
99 views

What does this syntax involving Entity mean?

I came across a different style of input while defining functions. Though I tried playing with this form, I have not understood how to interpret this input. ...
7
votes
5answers
530 views

Appending _?NumericQ automatically to every variable of a function in the definition [duplicate]

I have a list of expressions as follows: as=Table[a[k],{k,1,500}] I would like to append _?NumericQ to every element of this ...
0
votes
1answer
41 views

Relations between Function Variables in Computations

I have the relation λ=c/f, respectively f=c/λ and a simple function n[λ_]:=λ²+1. I'd like to differentiate the function with respect to f, then plot it as a function of λ again. For this, I can define ...
6
votes
2answers
443 views

What does _. mean in patterns? [closed]

Here is a quick one, hopefully. I searched through different tutorials and documentation articles but haven't been able to find anything yet. What does _. mean? As ...
2
votes
1answer
58 views

Creating a function that differentiates rational functions

I want to create my own differentiation function Derivada. So, I already set some properties like: ...
10
votes
1answer
210 views

Optional pattern behaves differently in version 8, 9, and 10+

We recently ran into an issue when testing Rubi on older versions. It boils down to this simple example which I didn't dare to simplify further as I cannot test it in versions < 10 ...