# Tagged Questions

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.

72 views

### NDSolve emitting dvnoarg error [closed]

I'm trying to solve this simple system of ODEs, but it gives me the error "The function v1 appears with no arguments". I've attached a screenshot of the code. I hope someone could help me, I really ...
53 views

### Using Nearest on a 2D List (seeing extra parentheses)

I am working a problem involving colliding particles. I define a list of particle diameters (effectively a bin distribution). I need to know if two particles collide, in what bin diameter should I ...
227 views

### How can I make a summary of all the commands of Mathematica?

I would like to have a simple way to get summary information about all the many commands built into Mathematica. How could I do this? Is there a site I may refer to?
149 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; ...
56 views

### RecurrenceTable [closed]

I got an error saying ...
33 views

### Assigning to a variable with a computed name [duplicate]

I wish to assign about a dozen variables to complicated expressions. to ensure that the correct variable is assigned to the correct expression, I’d like to do something resembling ...
68 views

### NestList and RandomChoice from a list of functions

I am tryingg to modify Chaos Game Fractals from Wolfram Demonstrations. The part I am having problem with is this. Original code: ...
44 views

### How to get array/list of results of RotationMatrix?

For most other functions, passing in a list of arguments will return a list of results. E.g. t = Range[0, 10]; m = N[Sin[t]] returns ...
78 views

### Ways to protect certain parts of expressions

I am currently working on a quantum mechanics problem where I try to find equations that relate different states of a many-body system. The states are described by sets of pairs of integers, like <...
95 views

### Cannot use Part in Pure Function [duplicate]

I need to select some lists in the nested list of form of {{1,2,3},{2,3,4}}. I have used Select to complete my work. But when I tried Position, it doesn't work. For example, ...
419 views

### Trying to calculate derivatives of spherical harmonics

I am trying to confirm what is shown on this website: http://functions.wolfram.com/Polynomials/SphericalHarmonicY/20/01/01/0001/ But when I type ...
137 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 ...
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 ...
87 views

### Form a matrix to have inequality elements

It looks like a silly question, but I could not find any answers online. Your help is greatly appreciated! Say I have two lists now. ...
69 views

### For Loop in Mathematica {n, factored form of x^(n)-1} for 95<=n<=105

I am new to mathematica. I am trying to write a for loop to print out {n, factored form of x^(n)-1} for 95<=n<=105. I have followed the directions of another for loop, and gotten the following ...
330 views

### Long list of similar rules

Given the following: ...
900 views

### Can't comment strings with '*)' inside it

I believe it's a bug in notebook's comment parser. I can't comment strings with *) inside it. Something like: ...
65 views

### Fastest way to make division between a number and elements in a list [duplicate]

I have a list y={{a,b},{c,d},...} of dimension {10^5, 2}, and number x. I want to divide only the second part of each element of the list by x, and have as result a new list {{a,b/x},{c,d/x},...}. ...
112 views

### Products of Differential Operators

I have a differential equation defined as the product of operators which I want to expand out into a polynomial in powers of $z\frac{d}{dz}$ $\qquad \prod_{n=1}^p(z\frac{d}{dz}+a_n)$ However when I ...
40 views

### Full superset not displayed on Manipulate slider

I wish to incorporate ODE solution with Bondary condition sets: ...
87 views

### Syntax error in debug mode

Bug introduced in 8.0 and persisting through 10.3.0 It appears that in debug mode, the \[Piecewise] symbol and its associated grid give a syntax error. For a ...
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 ...
243 views

### Associativity of /@ [duplicate]

Why are the following not equivalent: Map[Line, Map[(Print[#]; #) &, {{{2, 1}, {1, 1}}, {{-2, 1}, {3, 1}}}]] which produces ...
54 views

### Help for properly writing simple derivative expression

I need help to write the following expression (only 1 iteration): f(x) = ...some basic function... f[X0,...,Xp] = f(p)(x0) / p! What I have so far: ...
68 views

...
130 views

### Substitution in parameters to “Which”

Why in this expression ...
65 views

### How to get the outermost command evaluated first?

I have an expression like ToString[Stuff[...]]. I plan on having the Stuff[...] be manipulated as a string according to the output of other parts of the program. The problem is that Mathematica tries ...
153 views

### Array in Sum in Minimize - error “Part specification x[1] is neither a machine-sized integer”

Help please M = 10; z = Array[x, M] {x[1], x[2], x[3], x[4], x[5], x[6], x[7], x[8], x[9], x[10]} ...
88 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 ...
42 views

### How can I mix // with a function of two arguments? [duplicate]

I often find myself using // when playing around with expressions, but it is always cumbersome to have to switch to the full notation just to apply a function of ...
971 views

### Postfix Double Slash Notation with Multiple Parameters [duplicate]

Examples A convenient shorthand that I use frequently is the "double slash" notation to string commands together. For example, I can write: ...
105 views

### How a novice user better understand the Q/A [duplicate]

A novice user reading Q/A here: I sometime need to just understand the syntax and meaning of commands exampled here. where is the best place to find it?
434 views

### A documented syntax of FileNames doesn't work?

Documentation discrepancy present through 10.3 According to the documentation for FileNames under Details: However when I attempt to use this syntax I get an ...
93 views

### SyntaxForm not correctly parsed by FrontEnd

When using TagBox with SyntaxForm, I noticed sometimes it is not well parsed by the FrontEnd....
79 views

### Appending functions to a list [duplicate]

Could someone please explain the difference between these methods, and possibly a nicer way to get the first result? (This is a toy example and in my real program I'd like to use ...
253 views

### How to see abstract syntax tree of Wolfram Language expression

I mean, suppose I have this expression: 2 + 2 I want to get something like this: Plus[2, 2] as an output. I've tried FullForm, but this just evaluates 2+2 and returns 4. Is this even possible?
365 views

### Defining a function with parameters as variables

I have an expression V = (a[1] + a[2])b[1]. How would I define a function of a[1], a[2] and <...
1k views

### Incompatible Changes since Mathematica Version 7?

There is documentation of the incompatible changes made to Mathematica with each major release: Incompatible Changes since Mathematica Version 1 Unfortunately that documentation simply stopped ...
2k views

### V10's Operator Forms - what are they good for?

V10 introduces an operator form for several functions perhaps primarily due to their role in queries as part of introducing data science functionality. At first pass it seems a lot of effort to add ...
75 views

### Why can't I pass in a product of matrices in my modified matrixform? [duplicate]

In attempt to build a function that would work like MatrixForm but would wrap a matrix with brackets, I tried the following function: ...
154 views

### How would one minimize with respect to an unknown number of variables?

Say I had a function like the following: f[n_] := Sum[a + Subscript[b, k], {k, 0, n}] Such that ...
444 views

### What is the right way to write a function that includes other functions?

I want to include multiple sub functions: $b(x) = 10x$ $w(x) = s + b(x)$ $c(x) = x^2$ into two main functions: $ua(x) = w(x)-c(x)$ $ub(x) = w(x)-c(x)^2$ As a reaction to this answer, I wrote ...