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.
159
questions
2
votes
2
answers
130
views
'Update' and how to use variables to define patterns in functions' arguments...?
This seems like an obvious issue that I have nevertheless never encountered before.
In a package, I want to use a variable to define a pattern that is used in the definition of some functions. However ...
- 1,335
3
votes
2
answers
86
views
Part specification using list elements
How to use a list to specify part of another nested list mat? We don't want to write ...
- 4,370
4
votes
1
answer
59
views
How to specify the type/Head of the optional named arguments to a function?
I am trying to improve my own dsolver API. Currently it takes optional arguments.
Is it possible to specify that an optional argument should say be String only? Or List Only? Or Integer only? and so ...
- 116k
3
votes
1
answer
52
views
Is it possible to name a pattern within a repeating pattern during function construction?
Question
I would like to know if it is possible to have a named pattern within a repeated pattern during function desctiption. For example: f[(a_)..]:=
Why I am ...
1
vote
1
answer
128
views
How to make a pattern that matches only when one of the argument's Head is a Plus?
I am trying to set up rules as follows:
ClearAll[CircleTimes];
If the arguments are the same the output is zero:
...
- 8,417
5
votes
2
answers
329
views
Map a two argument function to every element on list
I'm new to use the amazing map function in Mathematica, and I've found it really elegant to program in simple lines of code. However, I'd like to perform more elegant stuff. I've found this question, ...
- 561
0
votes
1
answer
48
views
How to define a mixed pattern consisting of string and regular patterns for function definition (using SetDelayed)?
I'm kinda stuck here, and I could really use some help:
I want to define a function, let's call it quarterValue, that accepts a ...
- 122
1
vote
1
answer
52
views
Why this pattern can't be matched? [closed]
My code is {x,y,z}/.PatternSequence[x,y]->t.I think the answer is {t,z},while the output is still ...
- 71
3
votes
1
answer
215
views
Pattern matching with two variables - derivatives on 4-vectors
I am interested in pattern matching with two variables and not just one, and more specifically implementing derivatives on 4-vectors. In the case of interest the 4-vectors have two indices; one is in ...
- 4,163
0
votes
0
answers
46
views
How to specify specific (custom) function arguments
Suppose that I want to have a function that is evaluated only when a user-specific, predefined flag is given out of a list of possible flags. For example
...
- 763
1
vote
0
answers
104
views
How to test for arguments for a pattern that is of a positive Integer OR Infinity so that both filter through to the definition on RHS?
How can I filter an argument of a function so that definition works on positive Integers (y >= 0) or Infinity? It will ...
- 1,977
2
votes
0
answers
57
views
How to specify complicated patterns in function arguments?
Unfortunately, I have not found in documentation how to create complicated patterns in arguments of a function
Consider a toy example. Say, I would like to have a simple function
...
- 704
0
votes
0
answers
48
views
Detecting whether a function is initially defined with the form R[x,y] or R[x_,y_], etc
I have a very long code that may have errors in definition of functions and I want to trace these errors.
Is there any attribute or function to detect whether a function is initially defined in the ...
- 350
0
votes
1
answer
103
views
Matching a Dynamic Argument Pattern
times is a list of times i.e. matching {{hour_, min_, sec_Real}..}.
I want to call ...
- 750
2
votes
1
answer
75
views
Defining function with arguments in a specific pattern similar to Graphics[]
I'm trying to define a function that is of this form:
...
- 107
1
vote
1
answer
65
views
Denoting the whole in Position/Extract/ReplacePart
Position returns lists of numbers consumed by Extract, ReplacePart and others as "...
7
votes
1
answer
207
views
How to set deeper patterns in arguments within function definitions. For example if an argument must be a list of 1 or more strings
Suppose I want to define a function whose argument must be a List of only Strings and List must have at least one member. I know how to require that the Head must be a List but how does one qualify ...
- 1,977
4
votes
0
answers
112
views
Lint checker for overlapping or conflicting function signature patterns
In building a system like Mathics (or anything having the number of builtin functions of Mathematica) there are lots of function definitions. I would like to sanity check or lint check the pattern in ...
- 223
4
votes
0
answers
62
views
Preventing $-renaming of pattern names in lexically-scoped constructs
When you use a lexically-scoped construct like With or Function to perform replacements in an expression, Mathematica might ...
- 8,458
7
votes
0
answers
69
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:
...
- 27k
8
votes
2
answers
315
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 ...
- 1,092
0
votes
1
answer
91
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 ...
- 107
2
votes
1
answer
24
views
Refer to argument in condition for other argument
The condition for b here doesn't recognize a. How can I fix this?
...
- 1,073
0
votes
0
answers
115
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 ...
- 113
1
vote
2
answers
94
views
Unusual performance of the Cases function [closed]
Recently I was surprised by unusual performance of Cases function. The code
...
- 704
2
votes
0
answers
83
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 ...
- 8,458
7
votes
0
answers
129
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:
...
- 8,458
2
votes
1
answer
112
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 ...
- 350
0
votes
1
answer
84
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 ...
- 51
4
votes
1
answer
95
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 ...
- 309
6
votes
0
answers
116
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 ...
- 563
0
votes
1
answer
79
views
passing splice instructions
Consider some passing splice instructions using start,stop,step pattern
...
- 912
1
vote
3
answers
78
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 ...
- 2,092
0
votes
0
answers
19
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 ...
- 2,092
0
votes
0
answers
52
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:
...
- 11.5k
1
vote
0
answers
62
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 ...
- 515
5
votes
1
answer
83
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:
...
- 3,706
1
vote
2
answers
52
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:
...
- 1,977
2
votes
1
answer
86
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 ...
- 483
1
vote
0
answers
35
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:
...
- 8,417
3
votes
1
answer
431
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 ...
- 621
3
votes
2
answers
73
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:
...
- 257
1
vote
1
answer
41
views
FilterRules works in DateListPlot but not in Plot
I just experience the following problem (this is a MWE just to illustrate). First DateListPlot
...
- 5,495
2
votes
1
answer
106
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 $\hat{\theta}$.
...
- 529
2
votes
1
answer
77
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 ...
- 153
0
votes
1
answer
89
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
...
- 101
22
votes
7
answers
865
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 ...
- 687
6
votes
2
answers
220
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 ...
- 687
0
votes
0
answers
65
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 ...
- 65
1
vote
1
answer
408
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 ...
- 1,535