Questions tagged [core-language]
Questions on the basic structure of the Mathematica language (Wolfram language) including atomic data types, syntax etc
483
questions
4
votes
3answers
234 views
How to programmatically modify a function definition
I would like to know an efficient method (without converting Mathematica Code to strings and string processing) of modifying a function definition programmatically. For example, I would like to tidy ...
2
votes
0answers
85 views
Why Does Subsets[…,{n}] not Output a Packed List, Even Though it Doesn't Unpack?
Assume list is packed.
I expect Subsets[] is a structural operation because it depends on the number of elements, not on what ...
0
votes
1answer
21 views
Speak misses words when executed first time in new cell
Version->12.1.1 for Microsoft Windows (64-bit) (June 19, 2020)
ReleaseID->12.1.1.0 (6959458, 2020061902)
PatchLevel->0
When I evaluate for the first time in a new input cell:
...
3
votes
0answers
74 views
Vector arrow notation in Mathematica
I want a fast way to type vectors in Text boxes like this: $\vec a$
I can do this manually with ctrl+7+"-> "
which creates this
...
0
votes
0answers
14 views
How do I combine evaluated expressions with unevaluated expressions
I want this function
PrintEvalExpr[Sin[Pi/2]]
Which outputs
Sin[Pi/2] == 1
I can either not evaluate, or evaluate but not at ...
10
votes
2answers
239 views
i_:0|1 varies in v12.1: incompatible change or bug?
Just check
i_: 0 | 1 // FullForm
In v12.0 or earlier the output is
Alternatives[Optional[Pattern[i, Blank[]], 0], 1]
But in ...
0
votes
0answers
41 views
Extention of Times operation causes bug in Expand?
I have the following code in Mathematica 11.01 :
...
2
votes
1answer
43 views
Splice matching function arguments
Mathematica 12.1 introduces Splice that replaces the old way of using Sequence@@ to "melt" a list of entries. However, the ...
1
vote
1answer
64 views
How do I evaluate my functions over a range of values? [closed]
I want to use the list of data which will come from MapData1 (in code); the first element is Īø and second is Action(I). I want to use this Action(I) and Angle(Īø) in ...
3
votes
1answer
44 views
Evaluate a Number head as a constant function
I wanted to use the parameters of a function in a distributive way, so for example
In[1]:= Through[(Cos+Sin)[x]]
Out[1]:= Cos[x]+Sin[x]
It works without problems ...
1
vote
1answer
33 views
Help with Evaluation controll/hold all attributes?
I'm making a sort of symbolic derivator, which needs to take its formulas in unevaluated form.
...
1
vote
0answers
39 views
If it possible to define a “function” such that the normal form will have the arguments in order? [closed]
I'm looking for something that acts like this.
How could ord be defined for 2 arguments? What about n?
Since Mathematica is a term-rewriting system it should be possible, but all my attempts were ...
5
votes
2answers
167 views
Is it possible to pipe(afterthought apply function) with options?
For example, I have the following
...
8
votes
2answers
367 views
How can I plot a parametric equation with ±?
I want to draw a parametric equation with Ā± like the figure below:
But I don't get the result I want when I run the following code. What can I do to get it?
...
2
votes
1answer
63 views
odd output from DifferenceDelta
I would appreciate an explanation of why DifferenceDelta produces a complicated expression for a simple quadratic. I see that this is caused by the Real value <...
1
vote
1answer
38 views
Extracting argument of a specific functions in a large expression
I have a large expression, for example
Cos[x]Sin[y]Sqrt[1+z]/(1+x^2)-1/(1+y)
I wish to extract the argument inside Sqrt ...
12
votes
7answers
775 views
Getting the “root” Head
I have a dynamic list of function names, like {f1, f2, f3, ...}, and they will enter in computation in various forms ...
5
votes
1answer
92 views
How to label parameters in Manipulate
How do I label the "2" and "3" so they show "square" and "cubed" in Manipulate controls? The following is my code:
...
17
votes
6answers
1k views
A clean way to conceptually extract Parts from a circular list
I quite often run into a situation where I want to treat a list as a circular (repeating) list, and want to take a specific sublist of it, such as...
One past the end of the list:
...
7
votes
1answer
134 views
AtomQ[Counts[{a, c, d, b, a, c, b}]] gives True. Why?
I donāt understand this:
In[]: AtomQ[Counts[{a, c, d, b, a, c, b}]]
Out[]: True
It looks like an expression.
Does this have to do with the realization ...
1
vote
1answer
76 views
Implement a math command on a list of numbers [closed]
I have a set of numbers and would like to do the same math process on all of them.
Example:
data1={1,2,3,4,5,6}
Then have each number processed as Log(1), Log(2),.....
This seems like such a ...
6
votes
2answers
85 views
Assert no unevaluated function applications
Background
Suppose I have begun a fresh kernel session, and I have defined the following function alone:
F[x_, y_] := x + y;
One expected use of ...
5
votes
1answer
77 views
Plotting a NumericQ-protected function with the attribute HoldAll fails
Fixed in 12.1
This works:
ClearAll[f1];
f1[x_] /; NumericQ[x] := x;
Plot[f1[x]^2, {x, 0, 5}]
This does not:
...
6
votes
1answer
150 views
Are Hold attributes Mathematica's way to implement lazy pattern matching à la Haskell?
I'm reading this and I'm having a hard time understanding lazy patterns; in particular I'm baffled with the server-client toy problem and why there is a 'problem' of matching "...too early".
The ...
2
votes
1answer
75 views
Domain of `Sqrt[x]^2`
I'm just starting to work with Mathematica and this is simplified version of the problem I have: seems that Sqrt[x]^2 simplifies to just ...
1
vote
2answers
36 views
Assign numerical values to symbolic variables in a vector inside a do loop
I have vector k = {k1, k2, k3, k4, k5, k6}.
I would like to assign numerical values to the elements of k in each step of a <...
3
votes
0answers
92 views
Calling custom function from C++
I'm programming a project where I use multivariate symbolic polynomials. At some point I need to perform a PolynomialMod over a prime modulus, but the library GiNaC which I use works only over the ...
0
votes
1answer
37 views
is the behavior of WriteString surprising?
WriteString["temp.txt","this string"] returns Null but creates an open stream which is reused if you again ...
1
vote
1answer
75 views
How to clear all variables? [closed]
I have noticed that the old trick of using:
ClearAll["Global`*"]
does not appear to work anymore. It does not clear the values of any of my variables. I assume ...
3
votes
1answer
76 views
Understanding how List head works
I am trying to understand how Wolfram Language is actually meant to work and here is something that I fail to understand.
Apply[f, expr] replaces the head of expr by f.
So how come I get different ...
1
vote
1answer
44 views
How do I get my function to output only true case for conditions on its arguments
I am quite new to Mathematica and have an issue regarding which statement.
cut[x_, y_] := which[x>y, doFunctionX[], y>x, doFunctionY[]]
cut/@{X,Y}]
I wish ...
3
votes
1answer
50 views
9
votes
2answers
380 views
Using vtx[] instead of vtx
There're two ways to generate a random tree as 1 and 2 below. Both work fine here. So what's the reason to use vtx[] instead of ...
0
votes
0answers
85 views
I need a starter kit for Differential Geometry
In Modern Cosmology, the Geodesic Equation is described as:$$\frac {d^2x'^2}{dt}+\left[ \left( \{\frac{\partial x}{\partial x'}\}^{-1} \right)^l_i \frac{\partial^2 x^i}{\partial x'^j \partial x'^k} \...
-1
votes
1answer
56 views
What is the problem in this program? [closed]
The output is showing running only.
For[m = 0, m < 0.05, m++,
For[a = 5, a < 20, a + 1,
a1 = a*(a/2);
x[m] = a1
];
];
27
votes
2answers
709 views
Using the Wolfram Language in a Commercial Product
Background
I am currently consulting with a client that is using Mathematica to prototype a number of proprietary algorithms. Many man-hours of work have gone into the development of these algorithms ...
6
votes
3answers
489 views
Is $2x$ documented?
According to the official documentation of Times[], multiplication of $x$ and $y$ is represented as one of
x*y
xĆy
...
2
votes
1answer
73 views
Question about iteration [closed]
I have the following expression:
sol1 =
(11 + 3*Ī“ - 11*Īø + 4*m*Īø - 3*Ī“*Īø - 8*Sqrt[(-(2 + Ī“))*(-1 + Īø)*(1 - Īø + m*Īø)])/(4 + 4*Ī“)
I want to plug numbers into $ \...
14
votes
1answer
226 views
Memory leak in the system function: how to free memory without restarting the kernel?
$HistoryLength = 0;
Warming up:
TextSentences[StringJoin@RandomChoice[Join[Alphabet["Russian"], {" ", "."}], 100]];
No ...
0
votes
3answers
78 views
2
votes
2answers
180 views
Vectors and Matrices [duplicate]
Mathematica makes no distinction between columns and rows. Yet, that is a BIG deal in the classroom. Does anyone have a source that explains how Mathematica manages to make every vector a list and ...
10
votes
4answers
388 views
Operator currying: how to convert f[a,b][c,d] to {a+c,b+d}?
This question is related to this golfing question (but I'm not interested in golfing, only in functional operator composition):
How can we convert f[a,b][c,d] to <...
22
votes
1answer
229 views
Possible Memory Leak Issues in NestWhile
Consider the following code snippet:
NestWhile[{#[[1]]+1,Pause@.001;ConstantArray[0,{100, 100}]}&,
{1}, (#[[1]] <= 10000) &, 2]
In theory, when ...
2
votes
1answer
82 views
Basic question regarding returning values from user-defined functions [closed]
I'm new to Mathematica today. I would like to write a function that will implement the following pseudocode:
f[x_]:=
Do something
return y
I have searched ...
6
votes
1answer
99 views
Can I stop a running NDSolve calculation without losing the data it obtained so far?
I would like to solve a system of ODEs numerically using NDSolve on an interval {t,t0,tf}.
For the systems I currently solve, ...
1
vote
0answers
67 views
Can I store output data in the Notebook file? Specifically output from NDSolve[ ]
I am having some outputs from NDSolve of the form
{{xāInterpolatingFunction[ā¦], yāInterpolatingFunction, ā¦ }}
and the ...
13
votes
2answers
3k views
The Wolfram Kernel must be activated for WolframScript to use it
I'm using the free Wolfram Engine for developers, but somehow I cannot activate it.
...
3
votes
2answers
241 views
Print characters from list with a For-loop
Suppose I have the list
primary = {"b","a","e"}
I want to get the following output with a For-loop (or While-loop)
"b"
"a"
"e"
My code is:
...
11
votes
1answer
904 views
Row vectors and column vectors (Mathematica vs. MATLAB)
As far as I know, Mathematica does not distinguish between row vectors and column vectors: all vectors are seen as lists. I know ways to bypass this as suggested in Product between a column vector and ...
1
vote
1answer
198 views
Error plots in MMA 12.0
Suppose I have the following data and associated quartiles:
data = RandomReal[{0, 1}, {40, 10}];
qs = Quartiles[data]
I want to make an ErrorListPlot from the ...
