Questions tagged [core-language]
Questions on the basic structure of the Mathematica language (Wolfram language) including atomic data types, syntax etc
459
questions
2
votes
1answer
68 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
24 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
52 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
61 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
74 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
42 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
47 views
9
votes
2answers
370 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
56 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
];
];
26
votes
2answers
519 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
481 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
208 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
76 views
2
votes
2answers
127 views
Vectors and Matrices
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 ...
6
votes
1answer
301 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
221 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
77 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
55 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 ...
7
votes
1answer
956 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
146 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
632 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 here Product between a column vector ...
1
vote
1answer
166 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
221 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
227 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
34 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
129 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
357 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
57 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 ...
10
votes
4answers
565 views
What is the accessibility of a package's `Private` context variables?
I've been reading up on how Mathematica handles contexts, $Context, $ContextPath, and a few of the tutorials they have on ...
3
votes
1answer
83 views
How to trace value assigned to local variable(variables in Module)?
Bug introduced in v10.1 or earlier and persists through v11.3
CASE:4240757
Here is my code:
...
1
vote
0answers
92 views
Design completion idea for Position [closed]
This is not exactly a question but rather a suggestion for a design which I think would greatly improve Mathematica. Before I put this to Wolfram Research I would like to see what other people think ...
1
vote
2answers
110 views
Computation with arrays of numbers
My code is
m = RandomVariate[NormalDistribution[], 100];
c = 0.1;
f1 = RandomVariate[NormalDistribution[], 100];
F = Sqrt[c]*m + Sqrt[1 - c]*f1;
I would like to ...
0
votes
2answers
34 views
My function for computing a partial derivative generates an error message [closed]
Apologies, I'm still new at Mathematica. I have defined the function
...
1
vote
2answers
62 views
Using a Do-loop to find divisors mod 13 [closed]
I want to check sum of divisors of i mod 13 fori = 1 to i = 20. I tried writing a Do-Print ...
10
votes
1answer
140 views
Why does Success[…][key] work and Failure[…][key] doesn't work?
I'm trying to figure out what is a quick way to add error reporting to my user defined functions. I was experimenting with Success and ...
6
votes
2answers
123 views
Converting prefix to infix
Is there a way in Mathematica to convert prefix to infix notation (where precedence order is preserved)?
For example, how would I convert S[a, S[b, c]] to ...
3
votes
1answer
53 views
Is using Length more efficient than using === as stopping criterion?
I am using
NestWhileList[
f[#, elems]&,
pairs,
Length[#1]<Length[#2]&,
2, Infinity, -1
]
to generate all suitable subsets from ...
1
vote
2answers
88 views
Change the output for `Times`function
When I have an input like:
1/2*k
The output is:
How to change the output of Timesfunction to see this result:
Another ...
1
vote
1answer
71 views
Defining iterative algorithms [closed]
Assume the iterative algorithm of interest to be as follows:
...
3
votes
2answers
80 views
Iconize behaves in a confusing manner
When I evaluate Iconize[Range[10], "range10"], it returns an icon labled "range10", which if evaluated returns ...
12
votes
2answers
122 views
Bad Float Counts? (Length[xs] != Total@Counts[xs])
In Mma 11.3, tallying floats with Counts seems to fail. (Tally works fine, and rounding fixes the problem.) Is this behavior ...
1
vote
1answer
38 views
using strings from a header row as “pointers”
Suppose I have a list like:
data={{"product","amount","price"},{"A",1,100},{"A",3,100},{"B",5,200}}
I could use a Map to calculate over each row the "amount" * "...
0
votes
0answers
61 views
Implementing a function that exhibits linearity
I am trying to define a function $\mathbb{E}_t$ such that $\mathbb{E}_{t}[f[x_{s}]] = f[x_{s}]$ if s<=t, and $\mathbb{E}_{t}[f[x_{s}]] = \mathbb{E}_{t}[f[x_{s}]]$ if s>t. $\mathbb{E}_{t}$ is ...
0
votes
0answers
88 views
Is there a direct way of adding two random step size lists
As shown in the figure, I have three lists a,b and c. I want to see whether a + b +C0= c(here C0 is a constant).
Since list a and b have varing step size (...
6
votes
2answers
164 views
Flat attribute : example I don't understand
I am just beginning to learn about attributes of function in mathematica.
I saw the example "Flat". But there is something I don't get :
...
2
votes
1answer
75 views
Inspecting Mathematica object
I'm using ProofObject for my question, but it applies to other objects too.
FindEquationalProof returns ...
