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.
135
questions
0
votes
2answers
65 views
Unusual performance of the Cases function
Recently I was surprised by unusual performance of Cases function. The code
...
2
votes
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
votes
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
votes
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 ...
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
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
votes
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 ...
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
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:
...
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
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
vote
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
votes
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 ...
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
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
votes
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
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
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
votes
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
votes
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
votes
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 ...
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
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
vote
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,...
0
votes
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
votes
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
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
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
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
64 views
Respecting excluded index in sum
I'm using a function involving a sum where some indices are excluded:
...
3
votes
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
votes
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
votes
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
votes
1answer
87 views
Why is { } interpreted as an option in my function? [closed]
I don't understand the output from:
...
1
vote
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
votes
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
votes
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
votes
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
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
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
votes
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
votes
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
...
0
votes
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
votes
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
votes
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
votes
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
votes
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.
...
