# 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.

165 views

### Replace For with If in Mathematica way

I have this code: ...
107 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) ...
132 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. ...
48 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 ...
19 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 ...
57 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 ...
41 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 ...
53 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 ...
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. ...
453 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: ...
52 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. ...
27 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? ...
41 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 ...
116 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 ...
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: ...
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[]; ...
52 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. ...
56 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] ...
144 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 ...
55 views

### How to assign options to a variable?

I want to redefine a function similar to Plot like this: ...
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 ...
172 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. ...
2k views

### Superscript prime symbol

x\[Prime] looks like $x_{'}$, ugly right? Is there a way to make a symbol with prime to look like $x'$? That's what I'm trying right now: ...
162 views

### Why is Reap result nested? [closed]

A minimal (toy) example for my question: i= 1; Reap[Do[Sow[i = (i + 1)^2], {4}]] (* {Null, {{4, 25, 676, 458329}}} *) I presume the entire result is a ...
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 ...
37 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 ...
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 ...
58 views

51 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 ...
364 views

### Where did I go wrong with my implementation of the trapezoidal rule?

One method for doing quadrature, called the trapezoidal rule, improves accuracy by connecting the points on the curve corresponding to the points of subdivision with line segments, forming trapezoidal ...
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 ...
1k views

### Problem with Fourier coefficients

I have just started using Mathematica with v9.0. I am trying to follow a computation from a book on Fourier series with the function $f(x)=x$ on the interval $-\pi < x < \pi$. Here is the code ...
51 views

### Using the Nest function — Confusion on my output

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

### Syntax Error for the following code

I have the following code in mathematica ...
48 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 ...
900 views

### Calling Table with custom iterator

I often find myself in situations where I, for example, need to build a table for some expression, but want to set the number of points rather then the step size, so the code ends up looking like this ...
86 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. ...
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 ...
72 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? ...
8k views

### How do I identify the source of a “Tag times protected” error?

I have some code that looks like Table[ a = 1; b = {2, 3} c = i;, {i, 2} ] which gives an error: Set::write: Tag Times in c {2,3} is ...
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 ...