16 questions linked to/from Understanding Villegas-Gayley
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### How to make a contextual variable?

I have a question that would be trivial in OOP, but I am a newbie to programming in Mathematica, so I'm wondering how to deal with it. Basically, I want to create a package which basically involves a ...
178 views

### How to prevent Mathematica from complete evaluation of special functions?

Recently I tried to check a result of integration which should be a linear combination of the Riemann $\zeta\;$-function at various arguments, the coefficients of the combination being of primary ...
179 views

### Unexpected behavior when directly assigning to DownValues

I'm encountering some unexpected behavior when assigning to DownValues. When I assign two definitions for test[1] as below, ...
523 views

### Mathematica unable to solve easy differential equation $y''+y\,y'=0$ with initial conditions $y(0)=1, y'(0)=-1$

Trying to solve the following: DSolve[{y''[x] + y[x] y'[x] == 0, y[0] == 1, y'[0] == -1}, y[x], x] leads Mathematica to declare that no analytic solution exists <...
331 views

### Why do subsequent evaluations seem to be stopped by a False Condition (/;)?

Exploring another problem and this example of @halirutan, I came across an evaluation behavior I don't understand. When g[] below is evaluated the first time, <...
165 views

### Why does Block reset Attributes?

Not even "formal symbols" such as \[FormalX] are guaranteed to always be symbolic. Their Protected argument is forgotten when ...
208 views

### ConversionRules and style inheritance

Take the LaTeX-Article stylesheet stylesheet = FileNameJoin[{"Article","LaTeX-Article.nb"}]; Compare these outputs ...
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### Multiple down-values with exactly the same lefthand side

I was working on an answer to this question, when I was sidetracked by what I bring up here. I wanted a function, which when given a string representing a binary number, would convert the string to a ...
276 views

### How to find out what files are touched when Get is called?

Is there a way to capture all package files touched whenever a package is called via Get, Needs, ...
212 views

### Capturing an F1

I teach an Intro to Mathematica course, and one of the things I try to reinforce early on is just how helpful Mathematica's help is. In the very first lab for the course, I even give the students a ...
108 views

### How do I extend (prepend or append to) an existing TagSetDelayed rule? [duplicate]

I have a TagSetDelayed rule associated with, say, tag: ...
631 views

### Prevent graphics from rendering inside a held expression

Assuming each odd line is input I would like the even lines to be the output of the following lines. In the above the Graphics are inside ...
2k views

### How to perform a depth-first preorder traversal of an expression?

Mathematica provides functions that perform a depth-first postorder traversal, or which use such a traversal, including: Scan, ...