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.

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39 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: ...
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0answers
59 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
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1answer
64 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: ...
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2answers
45 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: ...
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1answer
56 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 ...
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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: ...
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1answer
119 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
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2answers
64 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: ...
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1answer
30 views

FilterRules works in DateListPlot but not in Plot

I just experience the following problem (this is a MWE just to illustrate). First DateListPlot ...
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1answer
92 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 $\hat{\theta}$. ...
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1answer
65 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 ...
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1answer
60 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 ...
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7answers
661 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 ...
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2answers
188 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 ...
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0answers
48 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 ...
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1answer
88 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 ...
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1answer
102 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,...
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1answer
43 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 ...
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3answers
261 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 ...
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1answer
107 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 ...
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3answers
200 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, ...
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0answers
80 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 ...
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1answer
54 views

Respecting excluded index in sum

I'm using a function involving a sum where some indices are excluded: ...
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2answers
104 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-...
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1answer
132 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 ...
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1answer
40 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
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1answer
86 views

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

I don't understand the output from: ...
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2answers
87 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
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1answer
120 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 ...
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1answer
91 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. ...
6
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5answers
445 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 ...
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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
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2answers
432 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 ...
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1answer
52 views

Creating a function that differentiates rational functions

I want to create my own differentiation function Derivada. So, I already set some properties like: ...
9
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1answer
205 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 ...
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0answers
55 views

Functions definitions with variable arguments

How do you define a variable amount of functions with a variable amount of arguments? I don't get the reference at all : ...
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2answers
437 views

why doesn't this work to screen for Boolean inputs?

I routinely sanitize the inputs to a function using this sort of technique: funcI[x_Integer] := Print[x]; But it doesn't work with Booleans. ...
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0answers
38 views

Defining functions with pattern as argument

I want to define a function such that f[18/17 h[y][z]] = 18/17 z for any function h[y][z]. I first tried with ...
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1answer
144 views

Can the pattern “_.” be used in head?

The standard usage of the pattern _. seems usually used in the parameter, for example, f_[a_,n_.]. I wonder if such pattern can ...
6
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2answers
3k views

How to restrict the domain of a function

I realize this question has been asked many times, but I am fairly new at Mathematica and the other answers are very complex, and certainly too complicated for this simple code I am trying to write. ...
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1answer
132 views

NIntegrate fails because of symbolic evaluation [closed]

The following function can be plotted without any issues, say with ContourPlot, but NIntegrate fails because it tries to ...
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0answers
223 views

About the OptionsPattern[] approach of inheriting Options

Szabolcs showed in this post, that there are possibly two approaches to inherit function options. He recommended the Join approach. At first, I agreed. But today I ...
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0answers
44 views

Apply same type checking to every argument [duplicate]

Consider the following function which takes 10 arguments. f[Io_, {θ_, ϕ_}][{x0_, y0_, z0_}, d_][h_][L_][ω_] I know that all of these are of same type. I would ...
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1answer
73 views

How to require that a function argument be a pure function or a function-style replacement rule?

I'm trying to write a function whose first argument must be another function, defined either as a pure function or a function-style replacement rule. I don't know how to specify a condition on the ...
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1answer
62 views

How to turn a ruled pattern into a multivariable function [duplicate]

Fix m=2. My code generates a pattern like this one (n=2): ...
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1answer
94 views

Testing if list elements are numerical

I want to define a function with an argument, which is a list: m = 10; a = Table[k,{k,1,m}]; TestFun[listArg_] := Sum[listArg[[k]],{k,1,m}] Now if I run the ...
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1answer
68 views

Extra empty lists as function arguments

Consider the following piece of code: ...
3
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1answer
85 views

A pattern involving Times

If I define (this is 10.0.0.0) w[x : Times[xs__]] := {x, xs} w[x : h[xs__]] := {x, xs} Definition[w] gives me ...
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1answer
227 views

Function with number of arguments as parameter

I would like to write a function that generates the expression $\sum_{i_1,\ldots,i_L} f(i_1,\ldots,i_L) \left(s_{i_1}\ldots s_{i_L}\right)$ where $i_j\in \left\{0,1,2,3\right\}$ and $s_{i_j}$ are ...
4
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4answers
175 views

How to tell the dimension of an argument function

Let's say I'm trying to write my own gradient operator function. If I know the function is going to be $\mathbb{R}^2\rightarrow\mathbb{R}$, I could write ...