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

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6
votes
2answers
213 views

Why does Mathematica appear to change the head of certain expressions?

I don't know if the question trivial or not (if so I will delete it), but here is what I have: I know that x x (* x^2 *) Looking at the full form gives ...
14
votes
2answers
362 views

Can't get Append to append a record (association) to a dataset

The Documentation Center item, Computation with Structured Datasets, implies that Append has been extended in V10 to work with datasets. But not on my computer. (I ...
35
votes
2answers
922 views

Why is the new PositionIndex horribly slow?

This issue has largely been mitigated in 10.0.1. New timings for the final test below are: ...
21
votes
1answer
510 views

Shorter syntax for Fold and FoldList?

I find it tedious to write out the following: a = {1, 2, 3, 4}; Fold[f, First @ a, Rest @ a] f[f[f[1, 2], 3], 4] It ...
4
votes
1answer
147 views

Multiple down-values with exactly the same lefthand side

I was working on an answer to this question, when I was sidetracked by what I bring up here. I wanted a function, which when given a string representing a binary number, would convert the string to a ...
2
votes
1answer
50 views

Is the use of Block to temporarily override definitions inherently unsafe? [duplicate]

This may have been discussed before, if so, please let me know. Consider the following example: x = 5 Dynamic[{Clock[], x}] This will always display the ...
37
votes
4answers
629 views

What's the difference between Inactive and HoldForm?

In version 10, Mathematica not only added Inactive / Activate but also highlighted this change in the "New in 10" page (in Core ...
1
vote
1answer
115 views

Why is Return not forcing an exit from my function? [duplicate]

Here is simplified version of my code that exhibits the behavior troubling me: ...
82
votes
3answers
3k views

How to make use of Associations?

I have been curious about it for long. Now that Mathematica 10 arrives, I think it's time to ask the question: How the new Association data structure would be used ...
8
votes
3answers
737 views

Why are functions called first-class objects in Mathematica?

I've heard lots of people say a function is a first-class object in Mathematica. "Everything is an expression, including function." "There is no distinction between functions and data." Having read ...
7
votes
3answers
301 views

Implementing key-value associations in Mathematica 9 with inexact numbers for keys

I'm not sure of what type of problem my issue falls into, so I haven't been able to search forums with any success. If this has already been solved then my apologies! Essentially I'm trying to set a ...
1
vote
2answers
144 views

Unexpected Plot3D behaviour

The following illustrates what appears to be an incorrect Plot3D for this polynomial. I have forced the function to complex argument, changed ranges. In contrast, ...
0
votes
3answers
139 views

Identifying the symbol which has a specific value

I'm writing a program that will solve the value of 1 variable in a 4-variable equality equation, but the variable to be solved will depend on the user's input to the program. This is what I've come ...
2
votes
2answers
115 views

What is wrong with my use of Flatten? [duplicate]

Why does Flatten[f[g[a, f[b]], f[c, d]]] result in f[g[a, f[b]], c, d] I expected the answer to be ...
2
votes
1answer
293 views

Euler's method for a 2nd order ODE

This is my first post on this site. Also, I'm new to Mathematica. I'm trying to solve my first problem with Mathematica. It's about solving a 2nd order differential equation. I dont have the explicit ...
2
votes
1answer
96 views

Can a Symbol own OwnValues that don't evaluate when it's the head of an expression?

I believe this a question that most of us have encountered when we were beginners but forgot when we got more familiar with Mathematica. We know the notation $y=y(x)$ for functions, where $y$ here ...
0
votes
0answers
82 views

Using Wolfram Language without Raspberry Pi [duplicate]

What are the different ways I can start using Wolfram Language even though I dont want to use Raspberry Pi? Are there any convenient ways? I actually have a raspberry pi but I am trying to find ...
5
votes
4answers
844 views

How to completely delete the head of a function expression

Is there any way to completely remove the head of an expression function? For example, how would I remove the head Cos from ...
0
votes
0answers
59 views

?function-name does not return function help

For some reason when I use ?function-name to ask for help on a function, I got a very clinical breakdown of that function with its options and attributes instead of the blurb about the function: To ...
4
votes
1answer
119 views

How can I extract all the non-number symbols from an expression [duplicate]

If I have an expression, let us say something like this: Cos[3 x] + π/cofe Exp[y^(c z)] how can I get all non-number symbols in the expression which are: ...
0
votes
0answers
34 views

Unexpected results from Thread [duplicate]

I've run into an issue where threading two lists with a generic function, f: Thread[f[{{1,1}, {2, 2}, {3, 3}}, {4, 5, 6}]] ...
4
votes
2answers
162 views

Solve a system of M equations without specifying M

This post has been edited heavily in response to the comments: my initial question was very confusing. I am trying to write my game-theoretic model in Wolfram Language. There is only one remaining ...
2
votes
2answers
196 views

Issue with Set function

Tables often come with column headers. Indexing the columns with the header is a natural thing to do. Although a proper dictionary is the usual solution in such a case, I find it often practical and ...
4
votes
2answers
243 views

How can I avoid getting the error message Goto::nolabel in my code?

If anyone could suggest a reason why Label[begin] ... Goto[begin] would return Hold[Goto[Begin]], and (better) how can I avoid ...
18
votes
2answers
1k views

Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
3
votes
1answer
404 views

Is there the full Wolfram Language in Mathematica?

Today I read the new entry on WolframBlog with all it's nice little demos. I was realy interested in those with astronomic informations, but trying these with my own Mathematica I was irritated: ...
2
votes
1answer
93 views

Why there is no SlotSequence (##) form analogical to #[[ ;; n]]

I'm aware that this may be closed as offtopic but there are people around with "offtopic" knowledge :) So, in List context we can: ...
1
vote
0answers
70 views

Function behavior based on Head

I'm figuring how to implement a function behavior based on the Head of its argument. I mean ...
1
vote
0answers
62 views

Type Vietnamese in Mathematica

I type Vietnamese using UTF-8 Encoding but Text Display got error. How to type Vietnamese, Chinese in Mathematica. Please help me.
2
votes
0answers
105 views

How is Wolfram Language different than regular Mathematica? [duplicate]

From all I can see there seems to be no difference between "Wolfram Language" and regular Mathematica. Is Wolfram just a marketing rebranding of Mathematica or is there a new capability I am missing?
1
vote
1answer
125 views

Behaviour of Simplify when used with ArcTan and ComplexExpand along with assumptions

I am trying to simplify the slope of vectors with symbolic coordinates {x,y} using ArcTan[x,y] I am working with real X and Y I tried the following : ...
21
votes
1answer
304 views

Performance regression for Fold?

Bug introduced in 8.0 and persisting through 10.1.0 or later I noticed an over 10x performance drop on Mathematica v9.0.1 (as Oleksandr R. commented, also v8) compared with v7.01 for this code: ...
8
votes
1answer
260 views

Defining my own invisible operator

There are some invisible operators in Mathematica (\[ImplicitPlus],\[InvisibleTimes],...
5
votes
1answer
146 views

Problem with With [duplicate]

I am puzzled byWith. it does not seem to work. Please see example below (I have also used Evaluate and ...
3
votes
1answer
132 views

How to Override the Head of a Symbol

I was wondering if it is possible to override the head of symbols/operators. As a motivating example if I run: Then Ket will be returned. But lets say I want Bob to be returned instead of Ket. Is ...
0
votes
2answers
77 views

How can I make my output to be added to an existing list?

v = {{0, 0, 0}, {1, 0, 0}, {1, 0, 1}, {0, 1, 1}, {1, 1, 1}} For[i = 1, i < 6, i++, For[e = 1, e < 6, e++ 1, Print[Mod[v[[i]] + v[[e]], 2]] ]] I ...
10
votes
0answers
288 views

Create a new infix operator [duplicate]

It is well known that the infix operator @@ is used as a short form of Apply. For example, both ...
4
votes
0answers
53 views

Precedence of defined functions [duplicate]

When I define functions in Mathematica like: f[x_] := 3 f[x_Integer] := 6 How is the value of f[6] determined? It seems to ...
0
votes
1answer
80 views

Scheduled tasks not preserving order with Dynamic?

In studying the last Basic Example in the documentation for StartScheduledTask, namely ...
6
votes
1answer
114 views

Mystery with ValueQ

Consider the following ClearAll[jd]; ValueQ[jd] We expect False and get it. Now consider ...
7
votes
1answer
263 views

Treat all variables as local in a module [duplicate]

In most languages, any variable defined inside a function is considered local. ...
27
votes
2answers
1k views

Is Mathematica comparable to C++ for creating standalone applications?

At my university, I have a yearly essay. I'm allowed to use any technology for implementing it. I've been coding it in C++ with Qt. I thought of about Wolfram Mathematica because I have some ...
49
votes
3answers
3k views

Is Mathematica an Implementation of the Wolfram Language?

I am trying to figure out what the announcement of the Wolfram Language means for Mathematica. Is Mathematica an implementation of the Wolfram Language, or is it something else?
13
votes
1answer
332 views

Is everything in Mathematica ultimately stored as a rule?

My current understanding about Mathematica is that everything, at the lowest level, ends up as replacement rules. First question: is this true? Second question: does Mathematica "gloss over" these ...
8
votes
1answer
318 views

Find a word's linguistic pronunciation

Is there a way to get a word's linguistic pronunciation given the word as a string? I would like a function LingusticPronunciation such that, for example, ...
4
votes
1answer
437 views

Counting the number of operations performed during a calculation

I need to know how can I count the number of operations performed during a calculation of a CompoundExpression. In some of these expressions there are ...
5
votes
2answers
238 views

Overlapping pure functions

Let say I need and option for Plot: RegionFunction -> (-6 < #2 < 6 &) But I also want those ...
28
votes
2answers
849 views

Is there a name for #1@#2&?

Why does the pure function # @ #2 & have no name? I'm asking because sometimes I find inelegant to write expressions like ...
0
votes
2answers
255 views

Unwrapping a list when invoking a function [duplicate]

The minimal working example of my problem is as follows: l = {1, 2, 3, 4} f[a_, b_, c_, d_] = a + b + c + d Now, I'd like to evaluate ...
0
votes
3answers
103 views

How can I generate a generalized product to two lists in a special way? [duplicate]

Let's say I have two lists, and I'd like to generate a "cartesian product" from these two. Specifically Inputs: A = {{{1}}, {{2}}, {{1}, {2}}}; B = {8, 9}; ...