Linked Questions

453
votes
37answers
100k 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
2answers
131 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
76 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
57 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
63 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
161 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
211 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
178 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
46 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
1k 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}...
533
votes
19answers
133k 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 ...
129
votes
8answers
7k 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
317 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
302 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
62 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
262 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
749 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
63 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
147 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
812 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
319 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
205 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
366 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
258 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
124 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
153 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
117 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, ...
1
vote
2answers
116 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
257 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 ...
47
votes
2answers
2k views

How do you set attributes on SubValues?

SubValues, as discussed in a previous question, are declared as follows ...
7
votes
1answer
1k views

Difference between variables and functions

Forgive me if this question is very basic; I've learned Mathematica mostly by example. In most programming languages, there is a clear distinction between variables and functions: variables hold ...
3
votes
1answer
222 views

I want to compute the derivative of Black and Scholes option

Good evening to everybody, my question is about computing the derivative of a Black and Scholes option and to draw it. My code is ...
0
votes
0answers
39 views
2
votes
0answers
88 views

Does Mathematica have a method for achieving the same goals that Aspect Oriented Programming does?

I imagine that this question has been asked before, yet I'm not able to find an answer using the form of the question I believe might be asked. Is there a mechanism for duplicating the ...
3
votes
6answers
2k views

Defining an integer-valued function on an integer domain

This should be an easy question! I want to define a function with domain = the 12 integers {1,12}, with the values f[1]=31, <...
0
votes
1answer
57 views

How to erase definition introduced by using Set instead of Equal in Solve [duplicate]

When trying to solve a set of equations, I made a mistake by using = instead of ==. Now when I fixed the mistake, the equation ...
19
votes
3answers
857 views

Generating assignments and transforming code inside held forms when generating code

I have been playing with slightly above trivial code manipulations in Mathematica. I thought Mathematica would be great for this kind of work because of rule replacement and expression manipulation, ...
5
votes
2answers
7k views

Nested If statements

When I do this: Apply[(If[#2 == what, "yay", If[#2 == whoops, "nay"]]) &, {-5, what}] I get: yay But when I do this: <...
1
vote
1answer
470 views

NDSolve memory usage [closed]

I am trying to solve numerically a system of linear ODEs with some quickly varying driving functions. The basic command is: ...
2
votes
1answer
244 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) ...
2
votes
1answer
124 views

Clearing Problem with DSolve [duplicate]

Consider: This is a classic mistake (using a single equal sign) that has been discussed on Mathematica Stack Exchange before. I know that Clear[Derivative] will cure the problem. However, consider ...
5
votes
0answers
65 views

How to use the symbols in System`Private`? [duplicate]

Looking at Names["SystemPrivate*"] gives: I'd really like to use and look at the code for some of these symbols, e.g. ...
1
vote
0answers
85 views

How can PowerExpand be made to evaluate the ArcTan form that takes two arguments?

Consider c = Cos[phi]; s = Sin[phi]; ArcTan[c, s] // PowerExpand ArcTan[s/c] // PowerExpand which yields ...
1
vote
0answers
51 views

Creating an indexed set of functions with the indices in the function names [duplicate]

As the titles describes, I want to create a list of functions like the following, where the indices are not in the argument slots: ...
3
votes
0answers
231 views

Measuring Temp on a cubical using heat equation with Neumann and Dirichlet boundary conditions

I'm trying to solve 3D heat equation to understand how the temperature varies with time on cubical. i have mixed boundary conditions: Dirichlet on the bottom surface (constant Temp) Neumann on all the ...
1
vote
0answers
110 views

Pattern for a function of say 2 variables [closed]

How can I specify a pattern for an expression f for which say f[x,y] returns a value, ie is defined as a function taking two ...
2
votes
0answers
142 views

NDeigensystem returns error due to mesh discretization when calculating vibrations of a cantilever

There was an transcription error in the code I provided in a previous post: https://mathematica.stackexchange.com/questions/105713/ndeigensystem-returns-complex-non-hermitian-error-for-the-...
1
vote
2answers
129 views

I want to plot a list of points with specified t and x[t] coordinates [closed]

I have this code: ...
5
votes
2answers
6k views

How do I plot a solution of a differential equation?

I am having trouble generating a plot for a solution to my differential equations. I always end up with just blank axes. ...
1
vote
0answers
135 views

Solving a set of trigonometric equations [closed]

I've been trying to solve the following equations in order to plot Subscript[θ, 41] with respect to Subscript[θ, 2] from 0 to ...

15 30 50 per page