# Tagged Questions

Questions about how Mathematica evaluates expressions, tracing evaluation (Trace*), handling expressions in unevaluated form (Hold*, Unevaluated), nonstandard evaluation, etc.

214 views

### How can I have interruptible computations inside a manipulate?

Here's a perfect example of my problem: Manipulate[Pause[n], {n, {1, 10}, ContinuousAction -> False}, SynchronousUpdating -> False] It is illustrated by ...
145 views

### How would one return from a place of a pure function's body using Return?

From previous answers, replies and discussions it is known, while not formally documented (even in the most recent Wolfram Language Documentation Center), that Return can be used in a two-argument ...
103 views

### Strange behavior when setting NumericQ of a symbol

It happens both in v9&v10. If you try this a^0 a^0 (1/a)^(3/2) a^0 (1/a)^(5/2) Mathematica returns 1 (1/a)^(3/2) (1/a)^(5/2) It's trivial. However,...
187 views

### How to track Part of Symbol or How to symbolize Parts of Symbol without copying data

Let's create simple function: SetAttributes[h, HoldFirst]; h[data_] := Dynamic[Grid[data], TrackedSymbols :> {data}] test = RandomReal[1, {2, 2}]; h[test] ...
888 views

### Normal[Series[ ]] does not give a normal expression

Let us say I want to show how the Taylor's series for Sin behaves: ...
2k views

### Keep function range as a variable

Plot[2*x^2 - x + 2, {x, -1, 1}] plots a function of x from -1 to 1. As far as I can see, I cannot "save" this range in a variable: ...
389 views

### HoldFirst and inserting additional options into a Grid of Graphics

This is related to my earlier question, but is specific to an issue I have encountered with the use of the HoldFirst First, let's create some fake data for ...
277 views

### How do I “evaluate in place” programmatically? Need to evaluate Defer[] result in non-interactive setting

I need to evaluate the result returned from an external package, which contains Defer in it, but do this in a script without user interaction. I am not able to ...
379 views

### Why is CityData[All, “Coordinates”] failing?

When I evaluate CityData[All, "Coordinates"] Mathematica returns {Missing["NotAvailable"], Missing["NotAvailable"]} ...
184 views

### Why does this pattern with Plus not work for numbers?

I have a very simple question about redefining basic built-in functions, such as Plus. I'm pretty sure someone must have asked a similar question around here, but I ...
143 views

### Evaluate a expression split in a list

I have a list with this format {integer, sign, integer, sign, integer}, sign being one of these: Plus, Subtract, Times, Divide. For example, let's say: ...
498 views

### How Can Notebook Know When it Called by Another Notebook?

I would like a notebook to behave slightly differently depending on whether it is evaluated from another notebook; i.e., ...
222 views

### Why does Mathematica appear to change the head of certain expressions?

I don't know if the question trivial or not (if so I will delete it), but here is what I have: I know that x x (* x^2 *) Looking at the full form gives <...
144 views

### Explicit use of Evaluate not behaving the way I expect it to

I discovered a strange behavior of the Evaluate function. Case 1: ...
189 views

### Partial result of aborted evaluation of FullSimplify

When FullSimplify invoked on a large expression, it can run for hours. If I do not have time to wait, and abort the evaluation, I get no result, although, ...
682 views

### How do I make NotebookEvaluate work inside Button?

The following creates a button to select a notebook to run. When the button is pressed it seems that Mathematica finds the notebook but cannot evaluate it. The following error occurs Could not ...
263 views

### Graph does not evaluate some options when not displayed

How can I force Graph to evaluate all its options without actually displaying the graph itself? Evaluating the following code ignores the ...
804 views

### How is the Mathematica kernel structured internally, and how does evaluation work?

There is so much information available for Java--the internal details of (for example) the JVM memory manager are well-documented, and the performance considerations arising from its interaction with ...
547 views

### Why does Manipulate execute the expression twice?

When I execute Foobar[] in the code below and move a slider, the variable grad is printed twice. Why is this? How can I make the ...
201 views

### Where does a package have to be loaded?

I'm trying to solve a very tricky issue in my function. The function needs the NDSolveFEM framework. Here is a minimal example: ...
122 views

### Force evaluation of the right-hand side of a local variable definition

One can do expression = a + 1; f[a_] := Evaluate[expression] but how would one do something like this ...
222 views

### There is an issue with Manipulate in which it updates its argument twice in V10

I have asked this question before (here) and I thought that the issue is only when moving the Notebook window. It appears that Manipulate is working in weird manner. ...
138 views

### Showing “updating…” message while Manipulate is re-evaluating

Is it possible to show a fixed text such as "updating..." instead of the last result shown, when Manipulate is re-evaluating an expression (in a slow evaluation ...
262 views

### Machine Epsilon

I'm trying to evaluate the machine epsilon of my computer (see below). I wrote this: ...
115 views

### Why do certain fractional values in TriangleWave not evaluate?

While answering another question I discovered that TriangleWave does not automatically evaluate when given certain fractional values, specifically fractions with a ...
851 views

### Is there anything like a C pointer (or returning a reference) in $Mathematica$?

I want to do in Mathematica what the following does in C. ...