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Questions on the basic structure of the Mathematica language (Wolfram language) including atomic data types, syntax etc

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0answers
47 views

How can I better formulate a conditional statement?

To solve optimization problems I have seen this: Is there a more elegant way to do this with alternative conditional expressions? Is there something equivelant to ...
3
votes
1answer
44 views

Is it possible to write an expression A such that Evaluate[Evaluate[A]] is different from Evaluate[A]?

Mathematica is cool for all sorts of "magic tricks", but I'm trying to get an idea on how the core term-rewriting system works. Is it possible to make a term such that the output of its evaluation can ...
3
votes
2answers
101 views

The design implication of PD[X[ #, #, #, #], X[#, #, #, #]]

In Package KnotTheory, there's a function called PD[] that takes a tabulated knot and returns its PD codes, for example: ...
17
votes
1answer
242 views

Distinguishing Wolfram Language and Mathematica, the software

Which features are part of Mathematica, the software, and which features are Wolfram Language? I would say there has to be a line discriminating the two somewhere. One could say that Mathematica, in ...
14
votes
3answers
192 views

What is the difference between Set and SetDelayed when evaluating the RHS leaves it unchanged?

I thought there was no difference between f[a_] = 2 + a; and f[a_] := 2 + a; because the resulting ...
3
votes
1answer
89 views

Why did Set work instead of SetDelayed?

I started with the following expression a[t_] := -Pi Sin(Pi/2*t) where initial velocity is 2 Pi and initial distance is 1. ...
4
votes
1answer
54 views

How can I evaluate only the (bound) variables in an expression?

Given an arbitrary expression, how can I have Mathematica only evaluate the (bound) symbols, i.e. replace them by their respective values, but not do any further simplification/evaluation of the ...
0
votes
1answer
34 views

FunctionExpand vs FullSimplify

The documentation (v.11.3) says: "FunctionExpand is automatically called by FullSimplify." Why then does ...
1
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1answer
39 views

undesirable/buggy change in behavior of Limit in Mma 11.2?

The behavior of Limit changed in Mma 11.2, and I think it is in some ways undesirable or possibly buggy. Consider ...
1
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1answer
77 views

What resources can I use to become familiar with high level syntax?

I was reading a question about dropping higher order terms and realized that I have a serous gap in knowledge when it comes to the finer points of mathematica computational programming. Are there any ...
1
vote
0answers
42 views

What use is empty binding list in `Block[{},…]`? [duplicate]

Spelunking the Export function, I stumbled upon the following definition: ...
11
votes
1answer
107 views

stable sort for association?

Should I be able to use the "list of functions" approach to getting a stable sort of an association? In 11.1 I see, ...
7
votes
1answer
95 views

advantages of ApplySides?

Version 11.3 introduces ApplySides for situations where I usually use Map. What is an example where ...
3
votes
0answers
109 views

How to achieve with Mathematica the effect a closure has in other languages?

Motivation I want to write an auxiliary function (brief auxf) for testing the output of another function that evaluates its body repeatedly using ...
10
votes
2answers
104 views

Can a Symbol have more than one OwnValue?

The DownValues, UpValues, and OwnValues functions are all plural. In general, a Symbol may ...
4
votes
1answer
69 views

SetDelayed not working as expected

According to the manual, "A variable defined with SetDelayed is evaluated every time it is used". The code below suggests otherwise. ...
12
votes
1answer
139 views

Check if symbol is in core language

How can I check if a symbol is pre-defined by Mathematica, in a way that's backwards compatible with old versions? i.e. I would like some CoreLanguageQ[x_Symbol] ...
1
vote
0answers
32 views

Convenient value assignments in OOP

It is possible to implement OOP in Mathematica using something like obj=c[<|a->1,b->2|>] and it's convenient to extract value from the object by ...
0
votes
0answers
33 views

How can I extract the numerical value from the result of FindRoot [duplicate]

I've to use previous values of FindRoot to implement my program (recursively), but the type of the output from FindRoot is not a number. How can I extract the ...
4
votes
3answers
172 views

Keep only rules that replace integers with other integers

Let's say I have a list of replacement rules: List1 = {2 -> 3, b -> 5.5, 6.57 -> 2, 3 -> 4.5, 1 -> -1, 0.03 -> 0.5, 9 -> a} The desired ...
0
votes
2answers
47 views

Numerical integration with a fixed sampling size, skipping points [closed]

I have a large number of data points to integrate over numerically. I would like to sample only some of the points and use a rather large step size just to reduce computation time. Say the data ...
0
votes
2answers
40 views

NIntegrating in $n$ dimensions?

I need to make a function that takes a function $f$ and a natural number $n$ and returns the integration from -inf to inf in all the $n$ dimensions of $f(x_1,\cdots,x_n)$. With Integrate I would do ...
1
vote
1answer
42 views

any possible meaning to a “terminal” slash (/)? [closed]

I've been directed to the web page http://functions.wolfram.com/07.31.16.0001.01 The first statement in the formula is ...
-4
votes
1answer
71 views

how can i convert my matlab conde into mathematica or atleast convert the bisection program? [duplicate]

(Convert matlab code into mathematica code) (I'm fairly new to mathematica) (bisect function matlab code:) ...
0
votes
1answer
59 views

SplitBy and mod 2 [closed]

I wish to group semiprimes into groups with same parity. Mathematica does this well with SplitBy[ Select[ Range@ 100, PrimeOmega@# == 2 &], Mod[#, 2] &] ...
0
votes
1answer
100 views

Why 1 is not recognized as real? [closed]

I'm not understanding smth simple. Why is 1 not recognized as a real number in the second line?
3
votes
2answers
153 views

Writing a bisection root finder

I'm trying to make a simple function that will calculate roots of equations by using bisection method. My code isn't working right. Can anyone take a look and help me? Here is the code: ...
10
votes
1answer
330 views

What does the ToList function do, and where did it go?

I am trying to revive some code from 2015 (version 10?) which uses the function ToList. I can not find it defined in any notebook on my system (in fact, it only ...
-3
votes
3answers
186 views
11
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2answers
1k views

Can't understand one paragraph in Power Programming with Mathematica

In the chapter 7 of the Power Programming with Mathematica, there is a paragraph discussing the behavior of Set- functions: (page 205. (pdf version p. 224)) ...
1
vote
0answers
34 views

Is Construct introduced to replace Function application? Should it be treated as such an alternative?

I noticed that v.11.3 got released the other day; it was exciting so I went through the Summary of New Features in 11.3 to catch a glimpse of what's new and see if there is something I should keep in ...
0
votes
1answer
91 views

Why is Null printing?

I am making a function that will evaluate several other functions, using the same inputs, in my program and give me the results. I am using Print to do this (see ...
2
votes
1answer
87 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 ...
0
votes
0answers
33 views

Conditional access to entities in Wolfram knowledge base

I am trying to get the name of stars that are in a range of distances from the Sun. The Input I have tried is: ...
1
vote
2answers
35 views

How can I get a variable to be recognized as an array when computing expectation for multivariate distributions

The following expression works correctly: Expectation[ x^4, {x, y, z} \[Distributed] MultinormalDistribution[{0, 0, 0}, IdentityMatrix[3]]] But when I ...
7
votes
1answer
54 views

Abort but keep what was already calculated

This is a very general question I have about aborting a running computation but keeping what was already generated. Let's say that I perform a numerical optimization over a list of parameters. ...
1
vote
0answers
47 views

Is there a MaxPosition function? [duplicate]

The Max and Min functions return values, but I would like to have the position(s). Is there a standard function that does this? ...
1
vote
0answers
45 views

Why is Part designed to sometimes wrap the original head around the parts it extracts? [duplicate]

For me, the natural meaning of the function Part is "get the sub-expression at appointing position." It is quite unlike Take, <...
7
votes
3answers
282 views

Testing equality of graphics

Is there a way to reliably test the equality of two plots? Consider this: plot1 = Plot[Sin[x], {x, 0, 2Pi}]; plot2 = Plot[Sin[x], {x, 0, 2Pi}]; You'd think ...
3
votes
3answers
122 views

aggregate records across dates

Each record in a dataset includes a country name, a year, and observations (e.g., GDP) for that country in that year. I would like to generate a new dataset with one record per country (so I would ...
10
votes
1answer
256 views

Why use pure functions?

I've now read the official documentation of wolfram on (anonymous) pure functions, and the part about (anonymous) pure functions in the book "mathematica programming intro". I believe I understand ...
3
votes
2answers
93 views

What exactly do single brackets represent syntactically?

I'm trying to deepen my understanding of the mathematica language after having messed around with it for a long time. I'm reading the book "mathematica programming Intro". Unfortunately, I don't ...
7
votes
0answers
93 views

Mathematica lexer: Numbers

This is a follow-up question to Mathematica lexer: Symbols and UTF-8 and this it is about numbers. In Mathematica, we have a large number of ways to input numbers. They can contain a notation for the ...
1
vote
2answers
29 views

Evaluating a 2D function successively with each pair of values in a list of pairs [closed]

I have a table of parameter pairs a and b {{a1, b1}, {a2, b2}, ...} and I would like to ...
1
vote
0answers
49 views

Is this expected behavior for With? Should it be replaced by Block? [duplicate]

Evaluating the following piece of code, returns-as expected-3: g[a_] = a; With[{a = 1}, 2 + g[a] ] Why does the following ...
1
vote
0answers
41 views

ClearAll works on all variables except “h”? [closed]

I have a seemingly very strange problem. I have first defined a function $h$ as follows: h[x_]:=x^2 And I also defined some other variables. Then however, I ...
0
votes
0answers
41 views

Symbols in Mathematica (#, & etc) [duplicate]

I am constantly finding a lot of examples of usage of symbols # & etc in the code. But I could not find any information what they actually mean and how to ...
11
votes
0answers
113 views

Mathematica lexer: Symbols and UTF-8

Did you ever wonder why here on our site, there is a highlighting difference between f[argX_] := 1; and f[argα_] := 1; ...
5
votes
1answer
84 views

Is Depth[x, Heads->True] historical?

I randomly found that Depth has a boolean option called Heads: ...
1
vote
1answer
51 views

Functions defined with numbers

If I have defined functions as "A1", "A2" ecc. then I have many function as A+number, can I define a For cycle to call these functions (they have all the same kind of arguments) once? Something like ...