# Questions tagged [core-language]

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

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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 ...
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 <...
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 ...
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 ...
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 ...
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 ...
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 ...
47 views

### unexpected False for SymmetricMatrixQ

Why does the following evaluate to False? ...
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 ...
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} \...
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 ]; ];
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 ...
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 ...
73 views

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### Detecting errors and providing alternative results [closed]

I have the following piece of code: ...
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 ...
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 <...
221 views

### Possible Memory Leak Issues in NestWhile

Consider the following code snippet: NestWhile[{#[]+1,Pause@.001;ConstantArray[0,{100, 100}]}&, {1}, (#[] <= 10000) &, 2] In theory, when ...
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 ...
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, ...
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 ...
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. ...
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: ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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: ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
71 views

### Defining iterative algorithms [closed]

Assume the iterative algorithm of interest to be as follows: ...
80 views

### Iconize behaves in a confusing manner

When I evaluate Iconize[Range, "range10"], it returns an icon labled "range10", which if evaluated returns ...
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 ...
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" * "...
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 ...
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 (...