Questions tagged [core-language]
Questions on the basic structure of the Mathematica language (Wolfram language) including atomic data types, syntax etc
477
questions
0
votes
0answers
69 views
What is the meaning of this input? [closed]
Consider the following input to Mathematica:
v[{1}] = 10;
v[{2}] = 20;
v[{3}] = 30;
v[{1, 2}] = 50;
v[{1, 3}] = 60;
v[{2, 3}] = 70;
v[{1, 2, 3}] = 100;
How does ...
2
votes
1answer
40 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
55 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 θ and second is Action(I). I want to use this Action(I) and Angle(θ) in ...
3
votes
1answer
43 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 ...
0
votes
1answer
22 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
37 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
159 views
Is it possible to pipe(afterthought apply function) with options?
For example, I have the following
...
9
votes
2answers
361 views
How can I plot a parametric equation with ±?
I want to draw a parametric equation with ± 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?
...
asked Mar 27 at 23:34
Please Correct GrammarMistakes
3,6691 gold badge7 silver badges25 bronze badges
2
votes
1answer
46 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
34 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 ...
13
votes
7answers
768 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
80 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
133 views
AtomQ[Counts[{a, c, d, b, a, c, b}]] gives True. Why?
I don’t 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
73 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
84 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
72 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:
...
7
votes
1answer
147 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
72 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
26 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
75 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
73 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
377 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
70 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
649 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
483 views
Is $2x$ documented?
According to the official documentation of Times[], multiplication of $x$ and $y$ is represented as one of
x*y
x×y
...
2
votes
1answer
73 views
Question about iteration [closed]
I have the following expression:
sol1 =
(11 + 3*δ - 11*θ + 4*m*θ - 3*δ*θ - 8*Sqrt[(-(2 + δ))*(-1 + θ)*(1 - θ + m*θ)])/(4 + 4*δ)
I want to plug numbers into $ \...
14
votes
1answer
219 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
158 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
384 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
226 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
89 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
64 views
Can I store output data in the Notebook file? Specifically output from NDSolve[ ]
I am having some outputs from NDSolve of the form
{{x→InterpolatingFunction[…], y→InterpolatingFunction, … }}
and the ...
11
votes
2answers
2k 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
197 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:
...
10
votes
1answer
801 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
190 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 ...
11
votes
2answers
226 views
Selecting elements from a list where the order is set by another list
I have two lists, list A and list B. All of the elements of A are members of ...
8
votes
2answers
230 views
Surprising behavior of Part[ ]
Look at this list
list={1,2,3,4}
Obiously
list[[1, 2]]
throws the error:
During evaluation of Part::partd: Part ...
2
votes
0answers
46 views
one Dataset from multiple csv files
In one folder I have many csv files, all sharing an identical header. I can use SemanticImport to produce a Dataset from each ...
0
votes
1answer
137 views
How can I translate some JavaScript code into Mathematica code? [closed]
I am a programmer and would like to understand another field outside of the procedural thinking of if-else and for.
I would ...
16
votes
2answers
379 views
Around usage results
Why is
Around[10, 1]^2
+- 20
and
Around[10, 1] Around[10, 1]
giving 100 +- 14 ?
Just curious I would suspect them to ...
0
votes
1answer
60 views
Deriving a list of time differences from a column in a dataset and appending the list as a new column
I know it's a beginner question, but I've struggled with it for some time now and can't find a solution.
I have a dataset consisting of timestamps, where I've managed to compute the time differences ...
