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
151 views

Is it possible to assign numbers generated in an Error-Message?

If I have a differential equation of the form ...
0
votes
1answer
35 views

Replace argument of delayed function before it evaluates [duplicate]

How should I use replace so that f[x_] := x^2 Replace[f[3], 3 -> 1] OUT = 9 evaluates to 1, instead of 9? This way, the replacement of the argument is done ...
0
votes
1answer
70 views

Mapping over function's several parameters regions [closed]

About this post: Mapping multiple parameters of a function to specific values I wonder if the parameters a and b have ranges ...
1
vote
1answer
73 views

Generating sequence of averages of averages of partial sums

I have been given the following code that generates the sequence of averages (of the partial sums) of Grandi's series: ...
0
votes
0answers
55 views

Syntax for Neumann/Robin condition in NDSolve [duplicate]

I can't follow the logic of how a NeumannValue term is to be incorporated into a pde to provide a BC for NDSolve. The ...
0
votes
1answer
48 views

Experiment to test Infinite monkey theorem [closed]

I need to apply this experiment: For all numbers between [0,128] let be t {set total=0 repeat this experiment n times {set start=0 choose random number [0,255] lets be R While(R!=t) ...
3
votes
3answers
184 views

Replace For with If in Mathematica way

I have this code: ...
0
votes
1answer
54 views

Solving equations with change of variables is not working?

I have the following expression $$\text{expr=}\int_0^{\infty}\frac{C\exp(-\frac{mx^2}{\Omega})}{\Omega^m}\frac{1}{\sqrt{2\pi}\lambda\Omega}\exp\left(-\frac{(\ln ...
2
votes
1answer
120 views

Syntax f[x_][y_]

Need to understand the principle of the distinction between f[x_,y_] and f[x_][y_] It seems also that z[x_, y_][a_, b_, c_][α_, β_] := a (x + y)^b + c/(α-β) ...
0
votes
1answer
21 views

Is it the correct syntax with TransformedDistribution?

I define a function as f[x_] := ...;which is in fact the PDF of a random variable $X$. The PDF if given by $f_X(x)$. Let $Y$ is a random variable, which is the ...
0
votes
1answer
58 views

Why doesn't Mathematica solve this non linear (fractional) ODE? [closed]

a1 = NDSolve[{y1''[x] - 0.1 y1[x]^0.25 == 0, y1'[0] == 0, y1[1] == 1}, I get the following errors - Power::infy: "Infinite expression 1/0.^0.75 encountered ...
1
vote
1answer
47 views

List of Inequalities in RegionPlot with different colors [duplicate]

Starting from the example of the Documentation: RegionPlot[{x^2 < y^3 + 1, y^2 < x^3 + 1}, {x, -2, 5}, {y, -2, 5}] Which gives a nice plot with two ...
5
votes
0answers
137 views

Is there an internal logic behind short form symbols, such as @ (Prefix), @@ (Apply), /@ (Map), /. (ReplaceAll) [closed]

To me, function names (such as Apply and Map) seem more intuitive than their symbols (e.g. ...
1
vote
2answers
54 views

MMA gives error when a different PDF expression is used for the same distribution

I have the following MMA code. Note that the function I declared at the very beginning is the PDF of square of a Nakagami Distributed random variable. With $m=1$ and $P=1$, $f(h)$ becomes Exponential ...
2
votes
2answers
57 views

Substituting within a function definition that includes Simplify

I would like to define a function like myfunc[f_] := Simplify[(f/g)] where g will be substituted/replaced with the current value of g at the time of definition. ...
2
votes
2answers
457 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: ...
0
votes
1answer
57 views

Partial derivative of function of two variables

This question is not enlightening nor is it difficult. But some part of my notation or how I have defined my functions is messing up the D[f,x] function. ...
1
vote
1answer
45 views

Mathematica Empty Plot FourierSinSeries function

I'm trying to get a plot of different order Fourier series of the function x-1, why does Mathematica give me an empty plot? ...
2
votes
2answers
42 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 ...
9
votes
0answers
117 views

Is there a linter to help write good Mathematica code?

I don't do much real programming, but I've recently been turned on to Atom, which has linter plugins for over 50 languages to make coding easier (most drawing on pre-existing lint-like programs). In ...
0
votes
1answer
42 views

Applying multiple functions to a single column in a table

I've seen similar questions, but I'm having trouble applying solutions found there to my situation. My sorting function: ...
1
vote
0answers
46 views

Is it possible improve the code scanning beyond what SyntaxQ does? [closed]

Please, consider this package (* ::Package:: *) BeginPackage["HelloWorld`"]; a::usage="A"; b::usage="B"; Begin["`Private`"]; a=1; b= End[]; EndPackage[]; ...
3
votes
1answer
53 views

Undocumented “Output” alignment argument to “Column?”

In this SE question, Inheriting Stylesheets when using CreateDocument, I noticed the literal string argument "Output" to Column. ...
3
votes
3answers
145 views

How to get the long logic expression with a terse method

I have a long logic expression (x==2||x==3||x==4)&&(y==2||y==3||y==4)&&(z==2||z==3||z==4)&&(m==2||m==3||m==4) How to get it by a terse ...
3
votes
1answer
57 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] ...
1
vote
1answer
57 views

How to assign options to a variable?

I want to redefine a function similar to Plot like this: ...
0
votes
0answers
38 views

Syntax question for declaring variables [duplicate]

I have a very basic syntax question for declaring $X_{hb}$ a variable. f[Subscript[X, hb_]] := Subscript[X, hb] In mathematica instead of writing the ...
3
votes
3answers
173 views

how to convert a bundle of if statements into a simple one.

hi i am just trying to create a matrix depending on some specific conditions for which i designed these codes which work fine but i want to concise these codes. ...
5
votes
2answers
213 views

Why SetDelayed won't work

I'm trying to do this: Riffle[list = {a, b, c, d, e, f}, tem = RandomInteger[1, Length@list-1]] {a, 0, b, 0, c, 1, d, 0, e, 0, f} But I think this method is ...
1
vote
1answer
38 views

How to use Composition when the functions have two parameter

There are some basic instructions about Composition on this site, but I'm still confused on how to use it when the functions I am composing have two parameter, such ...
5
votes
3answers
220 views

Relational operators on vectors

How do I use relational operators on vectors? {1, 2, 3} > {0, 1, 2} (*outputs {1, 2, 3} > {0, 1, 2}*) More generally, I want ...
0
votes
3answers
60 views

Plotting with NestList[]

So I want to use the NestList[] function, but i'm not sure how to achieve this for a system of equations like I have here $P_{n+1} = (rP_n +sQ_n)(1 - \frac{P_n + ...
0
votes
1answer
52 views

Solving a System of Equations syntax confusion

I have a system of two equations which I would like to solve in terms of a third unknown variable $s$. ...
1
vote
1answer
48 views

Basic Syntax Question — Variables for a function

I am looking at the following mathematica code Subscript[ff, r1_, r2_, CC_][x_, y_] := (r1 x + r2 y) (1 - (x + y)/CC) Subscript[gg, r1_, r2_, CC_][x_, y_] := x ...
1
vote
1answer
104 views

Module that prints first m positive odd integers and returns the square root of the sum of them

I am working on this problem and I feel like I've come so close. Write a module that takes as input a positive integer m, prints the first m positive odd numbers and returns the square root of the ...
1
vote
1answer
31 views

Iterating my function by $4$ using NestList — Syntax Confusion [duplicate]

I want to iterate my function $f(x) = 13xe^{-x}$ by $4$ multiple times. That is, $f, f^{4}, f^{8}, f^{12},\cdots$. Using Nestlist[f,x,4] I can get $f,f^{(2)}, ...
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 ...
1
vote
2answers
102 views

Extract all elements from a list that belong to a set or have a set element as an argument

EDIT: Added that I want to extract not only the variables from a specific set, but also functions involving variables from a specific set. Given the set ...
1
vote
1answer
52 views

Using the Nest function — Confusion on my output

I have the following code and output where the original function is $f(x,a) = a^2 - x^2$. ...
-1
votes
1answer
58 views

Syntax Error for the following code

I have the following code in mathematica ...
2
votes
1answer
49 views

Recognition Power Head for numeric value

We know: Map[Head, {a, a^2, a^3}] (* {Symbol, Power, Power} *) and Map[Head, {2, 2^2, 2^3}] all of them will be known as ...
1
vote
1answer
88 views

What explains non-working (black) variables?

I'm a bit new in Mathematica 10.3 and have had strange problem. Sometimes, variables appear in black and obviously prompt and error when used. ...
1
vote
1answer
80 views

Double arguments and place of the underscore

Could someone explain me of this bit of code below is correct: Is it possible to define a function with a second bracket, see below, i.e. f[x_][y_]? And what does ...
0
votes
1answer
76 views

what do those signs #1, #1^2, #1^3, & mean here? [duplicate]

I have read common pitfalls page and the documentation page but I still don't understand what do those signs mean here? ...
2
votes
1answer
57 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 ...
0
votes
2answers
114 views

Referencing elements of ArrayRules

How do I call elements of ArrayRules by their indices rather than by Part[ArrayRules[list],i]? I'd like to call the element that ...
4
votes
1answer
45 views

Aliases for keys?

The syntactic sugar for alternatives in replacement rules is clean: {a|b|c-> 1, d->2} Are there any analogous shorthands for keys in associations. I want ...
0
votes
1answer
66 views

What does the syntax <<X>> mean? [duplicate]

What does the syntax; << X >> mean? Where X is a number? Cheers
3
votes
0answers
84 views
2
votes
4answers
137 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: ...