Questions tagged [pure-function]

Questions about implementing or applying functions which: (1) always yield the same result for the same input, (2) are independent of outside information, and (3) produce no side effects.

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Pure function on pure function

Given t1 = {2, 4, 8, 16}; t2 = {1, 5, 9}; First[Select[t1, # > 1 &]] First[Select[t1, # > 5 &]] First[Select[t1, # > 9 &]] can somehow be ...
116 views

How to call a list of pure functions/pure vector function? [closed]

In one dimension, pure functions work as usual: f = Function[{x}, 2 x] f[a] However, with a list of pure functions / a vector pure function this does not work with ...
1 vote
106 views

A way to generalize my code for this non linear ODE problem

I am trying to solve the differential equation $y''(x) = y(x)+\sin[y'(x)]$ using "Fixed Point Iteration" over the interval $[0,1].$ Now using central difference method I arrived at the ...
227 views

Using MapThread with pure function and variable number of elements

I have a variable size array of lists and would like to set up a MapThread of the lists with a variable pure function $\{\#1,\#2,...,\#n\}\&$ with $n$ being the number of rows in the array and am ...
218 views

How to apply the multiple composite functions to a list?

A minimum example is this: ls = {1 + I, 2 - I}; Max@Re[ls] Min@Im[ls] #[ls] & /@ {Max@Re, Min@Im} (*want {2, -1}*) The result is: ...
208 views

AppendTo in combination with pure function

spA = {}; spB = {}; spC = {}; AppendTo[#, {"Up", "Down"}] & /@ {spA, spB, spC} doesn't work in Mathematica 11.1.1. Why? What is an alternative?
76 views

How Can I Use an Element of a Tuple as an Argument for a Pure Function?

(If I should elaborate on the circumstances, tell me.) I want to do the following: Suppose I have a tuple tuple={x,4,something,...} and I want to define a pure ...
81 views

Same code behaves differently as a pure function and a function, and insider another function

I have a rule-transformer that takes a list of rules (and a list generator = {σ[z], σ[-1], σ[1]}) ...
58 views

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Define equations as a pure function with list as argument

I have these set of equations. The number of equations depends on $n,$ which I want to keep control of. The code that I have generates it using Table and equations generated by this does not take an ...
112 views

Generalize the code to more variables

I have this code it runs and gives me the solution. How can I make it more compact and If I want it to extend(generalize) it to more variables how can I do it. I had asked a similar question here (...
1 vote
72 views

Mapping two pure functions over different lists

Say if I have two lists of vectors of the same length, for example: u = {{1,0,0},{0,1,0},{0,0,1}} v = {{1,0,1},{1,1,0},{1,1,1}} I want to add (modulo 2) ...
1 vote
72 views

Why must the "&" symbol be placed inside function instead of outside? [closed]

The following code is taken from Wolfram Community "Quantum Error Correction: bit flip". ...
75 views

Memory leak with pure function and in the listable option of compiled function?

I'm using 13.0.0 for Microsoft Windows (64-bit) (December 3, 2021) When I repeatedly run the command ...
35 views

Use FoldList to successively ImageAdd regular polygons with between 3 and 8 sides, and with opacity 0.2 [closed]

This question is from Section 29 of "An Elementary Introduction to the Wolfram Language". The objective is to successively add regular polygons with between 3 and 8 sides, and with opacity 0....
245 views

Pure functions: currying for & notation

I looked up currying in Shifrin's book. He points out that currying can be used for pure functions using nested functions as in the following example: ...
115 views

Condition inside pure function

Why condition /; not work inside pure function? Suppose we have: ...
1 vote
217 views

Pattern matching tuples as inputs to pure function

I've been having an issue with functions which are supposed to receive as input a list of tuples. My troubles are two-fold: The function doesn't properly identify the pattern test I laid out in the ...
77 views

Pure function with pattern test

Is it possible to achieve pattern test inside a pure function? I have tried f = Function[{x_?NumericQ}, x ] but the error Function::flpar occured.
1k views

Pure function of lists

I need to create a function with two arguments f(s, l): s is a list of three integer like: s={1,-3,+5} and l is a list of lists of naturals of same length: ...
191 views

Pure functions failing in algebra

f[equation_] := Module[{}, ContourPlot[equation[x, y] == 1, {x, -2, 2}, {y, -2, 2}] ] equation = (#1^2 + #2^2) &; f[equation] The above code draws a circle....
82 views

How to define pure functions in matrix form?

I want to define pure functions x(#1,#2) and y(#1,#2) like But they aren't proper pure functions in the current form. How to modify the code?
1 vote
106 views

Nested pure function argument as table

I made a nested pure function Nest[(x^2)/ ((2x+1) + #)&, x,n] I would like that for each iteration the value of x increment of 1, to have something like \...
182 views

Slots inside nested pure functions

I'd like /@ instead of Table or Map. But let we have it inside pure function: ...
82 views

Sort a list using a scoring list with Switch [duplicate]

I have a minimal working example (MWE) list called listToSort that is a list of string triplets: ...
55 views

Sorting a list by increasing order algorythm [closed]

Im new to loops on mathematica,was wondering how could I create a function to loop through a list which finds the index of the smallest value of that list, makes a sublist from index 1 to that ...
1 vote
116 views

Drawing lines between coordinates in a list

Variable "l" is a list of coordinates and I am trying to draw a line from each coordinate to the next. But how? Apparently the last line isn't working. ...
94 views

MapAt with pure functions

Consider expr = Hold[1 + a + x + b + c + y + z]; idxes = {{1, 3}, {1, 4}}; Q1. I don't understand why ...
470 views

Construct a pure function containing built-in 'Sequence'

I guessed the output for (Sequence[#, 7]&)[3] should be Sequence[3,7] But my guess was wrong. See the screenshot: And I ...
127 views

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Splitting a list into sublists at provided markers

For a list of strings (or other elements): SeedRandom[3]; t1 = Table[RandomChoice[CharacterRange["A", "E"]], 20] ...
146 views

Evaluating a FittedModel over a list of values

Simplified version Using the simpler version suggested by @ulrich-neumann : ...
118 views

Why do these two calls to Apply return different results?

In the following example, why do these two calls to Apply return different results? ...
503 views

An anonymous function with constraints [duplicate]

I'm not very good at working with anonymous functions, a fact that has now come back to bite me. Suppose I have a function defined as follows: ...
601 views

How to condition arguments of a pure function?

I would like to exclude the point {x=0,y=0} in the function definition ...
51 views

MeshFunctions::invmeshf that resists other solutions

I'm trying to base mesh on the slope of the function. That's why there is a Cross of two partial derivatives. ...
102 views

Apply function modification to curried function

This is based on A function that modifies functions - well-defined operation?, a previous question of mine. Lukas Lang's answer of course works very well, but now I encountered the following edge case:...
314 views

How to supply argument to pure function when slot is already defined?

Here's an example of a pure function: 3^# > 100 & I can supply any value I please to the function, by placing that value after the prefix. E.g.: ...