Questions on correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and ~ characters.

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3
votes
2answers
146 views

Why does the iterator index in Table not work here?

I type the following command line Table[D[#1,varx[[i]]] &,{i,3}] where varx is a vector of dummy variables ...
3
votes
1answer
265 views

Using single replacement rule to convert algebraic expression

I have been trying this problems for hours and cannot find any helpful clues. How can I convert $Sinh[3\theta]+Sinh[\theta]$ to a rational function of x given $2Sinh[\theta] = x-x^{-1}$ by using only ...
3
votes
2answers
2k views

How does one specify Neumann conditions for NDSolve?

I have a series of functions defined in my notebook, and then want to use this to solve a diffusion-reaction type equation. At the moment, something like this works: ...
3
votes
1answer
59 views

Speedier Algorithm or Set of Steps to Increase Speed of Coefficient Generation

Good morning. I am working with higher powers of the Generalized Euler Number generating function $$\left[\frac{n}{\sum_{j=0}^{n-1}\exp{\left(w_n^jx\right)}}\right]^\alpha$$ where $w_n=\exp{\left(...
3
votes
1answer
134 views

How to get a best fit line on a scatterplot?

I know that I am supposed to call listplot inside of the show function but I can't seem to get that to work. The best I can get is this, which has the best fit line following the scatterplot. How do I ...
3
votes
1answer
86 views

Open a pop up window that runs a calculation in loop until it is closed?

How should I construct a code which opens a pop up window, displays a constantly updating image in it and is terminated once the pop up is closed? The constant updating would be an infinite loop of ...
3
votes
1answer
100 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: ...
3
votes
1answer
118 views

Dt acting on symbolic notational forms

This one must be simple, but I can't figure out a decent solution. Suppose, I have a symbol with a notational form applied to it, say OverHat[A]. Now, if I didn't ...
3
votes
1answer
116 views

Force ellipsis to print an end of an expression

For pedantic reasons I want to display an infinite sum of fractions in fractional form (i.e. as 1/x not as x^(-1)) with an ellipsis at the end of the expression. I have tried a number of ways and ...
3
votes
2answers
47 views

Better alternative to Hold/ReleaseHold for postfix application of Monitor

Trying to Monitor a process using the postfix notation, as in Table[Pause[n/10], {n, 5}] // Monitor[#, n] & fails: the ...
3
votes
1answer
152 views

Differentiating a Dot Product

I apologize if this type of question has been asked before, but a preliminary search turned up nothing. I would like to differentiate dot products. For example, consider taking a derivative with ...
3
votes
1answer
61 views

How to set similar constraints on multiple variables in Solve

In this equation: var = {x, y, z, m}; Solve[x + 2y + z + m == 14 && And @@ Thread[2 <= var <= 3], var, Integers] {{x->2,y->3,z->3,m->3},{x->3,y->...
3
votes
1answer
114 views

Binary decision diagrams (BDD) syntax error

I am new here (and to Mathematica) and would like to rebuild a simple binary decision diagram that I found here https://en.wikipedia.org/wiki/Binary_decision_diagram A code has been provided as part ...
3
votes
1answer
141 views

HSQLDB database webserver access

I need a database that runs its connection over http and not tcpip. The "HSQLDB (webserver)" jdbc driver should be able to do just that. The following code launces the webserver but the OpenSQLConnect ...
3
votes
1answer
69 views

Pathological behaviour when evaluating a sum

When I declare the function $f$ as follows: f[n_] := Sum[x/Sum[Sqrt[y], {y, 1, x}], {x, 1, n}]/n the input ...
3
votes
1answer
193 views

Levels and slots

I am struggling with levels and #, if I understand this I think I will be able to grasp the entire concept. ...
3
votes
1answer
139 views

Filtering the elements of an array to split them into two categories

So, I am new to Mathematica, and I am trying to write something that involves taking values from one array and separating them into two different arrays. My code for doing this is: ...
3
votes
1answer
88 views

Why minimization does not work with symbolic array as arguments

If I try to minimize with constraints a function of several variables, with Gamma regularized function involved in the constraints it seems to works, as shown below (this is just a dummy example ...
3
votes
2answers
130 views

Substitution in parameters to “Which”

Why in this expression ...
3
votes
1answer
114 views

Local evaluation works, CloudDeploy did not work

I a playing around with my programming cloud account. What I have found, interactive functions often are not working because there are several details that are not implemented into the cloud. So I ...
3
votes
1answer
110 views

Why is ^^ff not the same as ^^ToExpression[“ff”]?

I want to convert a hexadecimal string to a decimal (base 10) number: 16^^ff 16^^ToExpression["ff"] The 1st line returns the correct answer of 255, while the 2nd ...
3
votes
1answer
119 views

How to make InverseFunction work on function defined with restriction on arguments

This example works to define InverseFunction on the first argument of a function ...
3
votes
2answers
64 views

How to create assignments to OverVector programmatically

I wish to write a function that accepts two lists. The 1st argument is a list of lists, holding the components of a several vectors. Ex.: comp = {{a, b}, {c, d}}. ...
3
votes
0answers
53 views

Pre-define list of variables to set them in bulk

I understand this is likely tremendously simple, but I cannot work out how to do the following: vars = {b,c} *define variables* vars = {1,2} *set them* Then I ...
3
votes
0answers
91 views
3
votes
0answers
38 views

Java anonymous functions from JLink?

JLink is really great to act on Java objects and access Java static methods. I'm asking myself if there would be a way to have access to a more recent Java syntax that allows anonymous functions, ...
3
votes
0answers
61 views

Why is `Cell` > `Convert To` > `InputForm` not invertible?

I sometimes post code to PhysicsSE, and I usually convert it to InputForm first before posting, in order to avoid pages and pages of ...
3
votes
0answers
115 views

Assign variables from list inside With or Module

I have found that it is possible to assign variables from lists, as follows. r = {1, 2, 3}; {a, b, c} = r; b 2 However, ...
3
votes
0answers
527 views

NonLinearModelFit with Two Dimensional List of Weights

I'm currently trying to fit Planck's law (B[λ, T]) to measurements, thereby determining Planck's constant. I have a list of triplets containing wavelength, ...
2
votes
4answers
146 views

How to obtain the gradient of a function as a function?

The Grad function allows me to get the gradient of a function like this: ...
2
votes
4answers
622 views

Using the result of Solve in subsequent calculations

I'd like to know how to use the results of Solve in later calculations. Here's what I'm doing now: This is my expression ...
2
votes
4answers
270 views

Where did I go wrong with my implementation of finding a plane tangent to a surface?

I am working on finding the plane tangent to a paraboloid at a given point. My code: ...
2
votes
2answers
135 views

What is the meaning of Range[10] /. {x_ /; PrimeQ[x] -> x^2}? [closed]

I'm currently doing a unit at university that touched briefly on Mathematica, but the final exam will feature multiple choice questions from Mathematica (along with excel and matlab). This leads to ...
2
votes
3answers
1k views

Output of plots from within Do[ ] Command

I am wondering why the following does not plot the way it's written and exactly how does the Do[] function operate? I think I could be using it incorrectly. ...
2
votes
2answers
146 views

How to make Mathematica returns the exact expression I typed

I'm using Mathematica to compare some constants. Before playing around with those constants, I would like to check that I didn't make any mistake in typing them. So my question is the following: "What ...
2
votes
2answers
150 views

Using list elements as function calls ?

Is it possible to take elements of a matrix or list and use them as arguments of a function? I have a matrix of values, something like this; ...
2
votes
1answer
714 views

Why is EigenValues returning Root expressions? [duplicate]

This is the code I have: ...
2
votes
2answers
378 views

local variable naming & symbolic argument

I'm stuck here with my variable assignment in this scenario ...
2
votes
2answers
463 views

What is the meaning of “/.”? [closed]

I've looked to the built-in help of Mathematica, but I still can't understand the usage of /., like in the following expression: ...
2
votes
1answer
1k views

Indices and variable definitions in Mathematica

Does anyone know how I can do this in Mathematica? Just an example.. Defining indices and variables (defined over indices), "mapping" variables and indices: ...
2
votes
1answer
354 views

Syntax for integrating over limits specified by a Table

I wish to use NIntegrate to compute multidimensional integrals. However, I don't want to manually input the limits for the dimensions. I want to store the ...
2
votes
3answers
202 views

How do I interpret the following syntax?

I have been given some code with the following line PeriodicExtension[g_, x_] := If[Abs[x] < Pi, g[x], PeriodicExtension[g, x - 2 Sign[x] Pi]] I do not ...
2
votes
2answers
180 views

Extracting counts of contiguous zeros and ones from a binary array

I'm a novice with Mathematica, but you guys have been very helpful to me in the past. I have a binary array [100, J repetitions] consisting of zeroes and ones. I'd like to extract a histogram of the ...
2
votes
1answer
253 views

Difference between Map[f[#] + g[#] &, {a, b, c}] and Map[f[x]+g[x]&, {a, b, c}]

Map[f[#] + g[#] &, {a, b, c}] vs Map[f[x]+g[x]&, {a, b, c}] My question is: why is the output different? ...
2
votes
1answer
224 views

What is an alternative to using backticks in separating namespaces from function names?

What is an alternative to the backtick (`) in separating the namespace from the function name? Can the function be called without using this symbol? I think in ...
2
votes
1answer
39 views

A natural syntax for a Query that holds

Often I have an unevaluated expression in a RuleDelayed Key-Value pair and subsequently want ...
2
votes
1answer
61 views

Why do Wolfram Alpha and Mathematica give different answers? [closed]

I've just got my hands on Wolfram Mathematica and tried to see if I can figure out how to use it by myself. I've plugged in an integral $\int \frac{dx}{(1-x^2)^{2/3}}$, knowing that the result is $\...
2
votes
2answers
103 views

Simplify set-theoretic expressions [duplicate]

As I can get set-theoretic simplifications of expressions and corresponding Venn diagram for example ...
2
votes
1answer
108 views

Table of references [duplicate]

I have a list of variables (say a, b, c, d, e) that I want to assign in a single command. {a,b,c,d,e} = {1,2,3,4,5} would ...
2
votes
1answer
94 views

RegionUnion issues with many Regions

The new RegionUnion[] function is just what I needed if only I could get it to work. I have many non-overlapping regions that I will need to use as plotting domains ...