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.
167
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How to implement this in Mathematica？y=argmax{max{f(x,y),g(x,y),h(x,y)}}
There are three bivariate functions with respect to x and y. Slice x into 100 pieces from 0 to 1. Starting from each slice, calculate the function with respect to y. Find the maximum value of each ...
5
votes
1
answer
48
views
Assumptions about indexed variables
I am interested in the most efficient way to impose assumptions on indexed variables. In the following stylized problem, the following code
...
- 187
0
votes
2
answers
46
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Pattern for Matching for Numeric 3 Vector [closed]
I'm trying to write a basic molecular dynamics sim in Mathematica and would like to define a function calculateForces that takes two arguments. The first is a 3 vector for the coordinates of a ...
2
votes
2
answers
49
views
Is it possible to combine a default value in a function definition with type-checking, in case the optional parameter is actually given in a call?
1.) In a function definition, e.g.
...
- 2,778
1
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3
answers
68
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How can I write a function definition which gets another function as parameter whether the parameters of the function match a pattern?
One can write functions which depend on the type of actual parameter before they are actually called. E.g.:
...
- 2,778
0
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1
answer
53
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How can I distinguish between different structures of actual function parameters?
Overloading functions for different types of parameters is very powerful.
I can easily write different versions of a function depending on the function parameters being Integer, Real, Complex, Sring ...
- 2,778
9
votes
1
answer
201
views
How do I correctly apply patterns to function arguments using Pattern (:), PatternTest (?), and Condition (/;)
Given:
Clear[func];
listOfLists = {{a, b}, {c, d, e}};
listOfRules = {a -> b, c -> d};
I can discern between listOfLists and listOfRules using MatchQ:
...
- 973
6
votes
1
answer
298
views
A problem on the pattern (:) of Heads
I defined
Clear[f, g]
f[(h : Exp | Log)[x_]] := x;
g[(h : Log | Exp)[x_]] := x;
The code gives a weird result:
...
- 161
2
votes
2
answers
143
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 ...
- 1,375
3
votes
2
answers
108
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 ...
- 4,564
4
votes
1
answer
61
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 ...
- 127k
3
votes
1
answer
56
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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
139
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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:
...
- 8,667
5
votes
2
answers
390
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, ...
- 623
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1
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52
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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 ...
- 162
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 ...
- 81
3
votes
1
answer
221
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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 ...
- 4,188
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0
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53
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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
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0
answers
208
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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 ...
- 2,337
2
votes
0
answers
66
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
...
- 744
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
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votes
1
answer
106
views
Matching a Dynamic Argument Pattern
times is a list of times i.e. matching {{hour_, min_, sec_Real}..}.
I want to call ...
- 760
2
votes
1
answer
79
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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
67
views
Denoting the whole in Position/Extract/ReplacePart
Position returns lists of numbers consumed by Extract, ReplacePart and others as "...
7
votes
1
answer
212
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 ...
- 2,337
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 ...
- 245
4
votes
0
answers
68
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 ...
- 8,695
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:
...
- 30.2k
8
votes
2
answers
373
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
126
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
172
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
...
- 744
2
votes
0
answers
94
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 ...
- 8,695
7
votes
0
answers
138
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:
...
- 8,695
2
votes
1
answer
134
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 ...
- 630
0
votes
1
answer
88
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
97
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
117
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 ...
- 573
0
votes
1
answer
81
views
passing splice instructions
Consider some passing splice instructions using start,stop,step pattern
...
- 998
1
vote
3
answers
79
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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 ...
- 2,194
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 ...
- 2,194
0
votes
0
answers
53
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:
...
- 11.6k
1
vote
0
answers
63
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 ...
- 535
5
votes
1
answer
84
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:
...
- 3,766
1
vote
2
answers
54
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:
...
- 2,337
2
votes
1
answer
97
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:
...
- 8,667
3
votes
1
answer
506
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 ...
- 641
3
votes
2
answers
77
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