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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2answers
65 views

Unusual performance of the Cases function

Recently I was surprised by unusual performance of Cases function. The code ...
2
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0answers
54 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 ...
5
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0answers
73 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
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1answer
63 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 ...
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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
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1answer
91 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
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0answers
101 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 ...
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1answer
73 views

passing splice instructions

Consider some passing splice instructions using start,stop,step pattern ...
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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 ...
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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 ...
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0answers
46 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
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
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1answer
72 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
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2answers
47 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
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1answer
66 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: ...
3
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1answer
186 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
66 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
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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
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1answer
96 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
68 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
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1answer
64 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
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7answers
719 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
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2answers
202 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
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 ...
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1answer
134 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
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1answer
113 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
58 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
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3answers
272 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
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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
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3answers
201 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
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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
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1answer
64 views

Respecting excluded index in sum

I'm using a function involving a sum where some indices are excluded: ...
3
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2answers
128 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
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1answer
148 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
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1answer
41 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
87 views

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

I don't understand the output from: ...
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2answers
98 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
124 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
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1answer
98 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
498 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
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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
442 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
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1answer
55 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
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1answer
208 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
56 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 : ...
5
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2answers
456 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. ...
0
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0answers
40 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 ...
2
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1answer
157 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
4k 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. ...