Linked Questions

484
votes
37answers
112k views

What are the most common pitfalls awaiting new users?

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...
2
votes
3answers
88 views

Performing iterated integrals

I would like to define a function $f_n(x)$ and plot it with Manipulate. The function is defined by $$ f_{n+1}(x)=\frac{1}{\int_0^1(f_n(x'))^2dx'}\left(\int_0^xf_n(x'...
3
votes
2answers
241 views

What is the point of tagset /:? [duplicate]

I'm teaching myself Mathematica and came across tagset. So I followed the example in the link, but seem to be missing the point. All of the below give me the same answer after assignment: that ...
0
votes
0answers
80 views

How does Wolfram Language implement for enabling symbols to receive various forms of parameters? [duplicate]

How does the official implement a list/tuple of parameters that can be different in type and quantity as a whole? After re-read @Szabolcs's and @MichaelE2's comments. Finally, I accepted the ...
1
vote
0answers
98 views

Understanding TagSetDelayed

I was reading What is the distinction between DownValues, UpValues, SubValues, and OwnValues? and I started to be confused with the part "Upvalues" of the first answer. Some of my confusion comes ...
1
vote
0answers
65 views

What is exactly an element a[i] in mathematica? [duplicate]

I'm confused about the logic behind mathematica programming. We can have function that will be called doing $f[x]$, thus the element $f[x]$ can be seen as the return value of a function taking an ...
1
vote
1answer
275 views

Scope of dummy variables used in defining a function

I define a function and then define another function, using the same name for the dummy variables as I used for the first function. Will Mathematica use the first definition in the second definition? ...
6
votes
2answers
222 views

What makes a pattern more general?

This is a rewording of the question. The original post is below. How come that a pattern for an expression with a specific head is not more specific than a pattern for an expression with a generic ...
0
votes
1answer
269 views

Get imaginary part of symbolic expression [duplicate]

I define ψ1 = Sqrt[Subscript[ρ, 1][t]] E^(I Subscript[θ, 1][t]); ψ2 = Sqrt[Subscript[ρ, 2][t]] E^(I Subscript[θ, 2][t]); and ...
1
vote
0answers
47 views

Multiple Square Bracketed Function definition

I am familiar with the typical way of defining a function--such as f[x_,y_]:=x+y but I have not found a discussion of definitions such as ...
11
votes
2answers
2k views

Solve a nonlinear PDE equation with a Neumann boundary condition

I am trying to use Mathematica 10 to solve a PDE $$u_t=u_{xx}+u_{yy}+u(1-u),$$ in the unit disk $(x,y) \in D=\{(x,y):x^2+y^2<1\}$, with the Neumann boundary condtion $$\frac{\partial u}{\partial n}...
564
votes
19answers
143k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
133
votes
8answers
8k views

Can one identify the design patterns of Mathematica?

... or are they unnecessary in such a high-level language? I've been thinking about programming style, coding standards and the like quite a bit lately, the result of my current work on a mixed .Net/...
11
votes
2answers
346 views

Why is `D[a[b][c],a[b]]` equal to `1[c]`?

Background: I had the same issue as described here, and I went to extend Mr.Wizard’s code such that a[b][c] would be shown as $a_b^c$. Issue: To my surprise, ...
1
vote
1answer
401 views

VectorPlot3D of the Electric Field E as Determined from the Potential V

I am new to Mathematica and I am trying to create the electric field $F$ from the electric potential $V$ (using arbitrary distances) and then plot the subsequent vector graph to show that the electric ...
1
vote
1answer
63 views

How do we input powers of indexed variables?

I have tried (a[i])^2 and alternatively (a^2)[i] Apparently both seem to work, but I was wondering what was the right way ...
4
votes
1answer
291 views

How do I get Mathematica to recognize this simplification? (ReplaceAll pattern rule)

I want Mathematica to understand this $$(\sum_{k=0}^n a_k)(\sum_{j=0}^n b_j) = (\sum_{k=0}^n \sum_{j=0}^n a_k b_j)$$ I have tried this ...
0
votes
1answer
1k views

Compute the half width and full width at half maximum (HWHM / FWHM) of a mathematical expression

I have managed to compute the half width at half maximum (HWHM) and full width at half maximum (FWHM) of a sinc function through the code below. ...
2
votes
1answer
82 views

How to recall set variables in simple Product[] and Sum[] functions?

I'm new to Mathematica but have been trying to write a code that will define new variables based off of variables preset by a user. I'm allowing them to define a variable ...
0
votes
0answers
160 views

table parametric plot ode

I have a series of ODEs I'd like to plot (a double pendulum specifically) Where I'm comparing my own "handwritten" ODE to that of System modelers solutions. This is mostly an exercise to ensure the ...
10
votes
4answers
997 views

Finding Anagrams of given length from DictionaryLookup

What I'm trying to find are the 4 letter words in the Mathematica dictionary that have the most anagrams and the amount of anagrams these have each. But I can't seem to find all the 4 letter words in ...
16
votes
3answers
369 views

Why is the first argument of the SetDelayed evaluated?

In[1]: f=g; In[2]: SetDelayed[f[x_],x^2]; In[3]: ?f Global`f f=g In[4]: ?g Global`g g[x_]:=x^2 However, SetDelayed has the ...
6
votes
2answers
234 views

WL terminology: evaluate, call, invoke, use, etc

A WL (Mma) program is a sequence of expressions to be evaluated, which generally involves applying commands and functions to actual arguments. What is the accepted terminology for what I think of as ...
1
vote
1answer
509 views

Plot 3D doesn't show anything

Good Evening, I defined a function which is composed of other several functions. Mathematica compiles well but I can't get a plot and I do not understand way. Can anyone help me with the code and ...
4
votes
1answer
265 views

Define scalar quantity that squares to 1?

My equations contain different cases which differ only by some signs. So in order to work with all cases simultaneously, I introduce a placeholder for a sign: s[x] ...
2
votes
1answer
149 views

Why doesn't CloudDeploy work in my desktop

I have difficulty in making CloudDeploy in my desktop. Does anyone know why ? Thanks Here is what I see: Here is the code if someone would like to test ...
0
votes
1answer
326 views

How to map a function over a dimension in a matrix? [closed]

I have a function g[x,r] yielding a 3x1 vector, where x is a ...
5
votes
2answers
126 views

Custom opaque operator with custom axioms?

Is there any way to define a custom opaque operator/function in Mathematica that satisfies custom axioms, so that the Mathematica engine can perform simplifications using those axioms? For example, ...
2
votes
2answers
158 views

How to define a function whose argument is in the replace list?

As a simplified example: In[780]:= f[x_] := a /. {a -> x}; f[1] Out[781]= 1 This yields the correct result. But ...
7
votes
2answers
321 views

Apply ToString to a list of variables [duplicate]

I have data1 = {1, 1}; data2 = {2, 2}; datalist = {data1, data2}; I want to create a string list based on the variable names inside ...

15 30 50 per page