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

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6
votes
1answer
618 views

Evaluate while external command is being run [duplicate]

Possible Duplicate: Computing Many Slow I/O Operations I'm launching an external command with the Mathematica front end that takes two arguments: ...
4
votes
1answer
128 views

Pre and Post in a Block[]

Why does Block[{$Pre = ( 1 + #) &}, 1] produce 1 while ...
7
votes
1answer
193 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 ...
2
votes
2answers
1k views

Animation of Differential Equations from NDSolve with ParametricPlot3D and Evaluate

I have a system of differential equations (referred to as "s") and use NDSolve to obtain the solution. I substitute the interpolated functions for the original ...
0
votes
1answer
69 views

How can I restrict a notebook to evaluate only if I am user 'root'?

I am playing with openCL on Linux with an AMD gpu, and due to a glitch in the driver, I need to be 'root' to get stuff to work. Installation question here.
1
vote
2answers
151 views

How can define a set of nested parameters

I would like to know how I to define a function with a nested set of parameters (or whatever you would like to call it). For example, how would I get the following function ...
5
votes
3answers
251 views

First evaluation fails

I am fairly new to Mathematica (version 7), so please bear with me... I have duplicated, in Mathematica, a program that I originally wrote in C (it generates OEIS sequence A191837). The problem is ...
8
votes
2answers
216 views

Why does the name of a pattern affect the result of a transformation rule?

I was playing a little dirty, trying to get a template for defining a Curl[] operator. I wrote the following rule, which I knew was going to spit out a few ...
1
vote
2answers
102 views

What is the default file path used by the Put function and how do I pre-evaluate an expression to use in Put?

I have a problem of trying to store some output in an external file. In one note book I define a function f[x_]:=AdvancedCalculation, where this function generates ...
0
votes
1answer
142 views

Slow Dynamic Button Does Not Print [duplicate]

Possible Duplicate: Why do buttons with ChoiceDialog freeze the front end? Why is SystemDialogInput failing to return a save file path? Evaluation inside Button stops after some seconds I ...
18
votes
3answers
614 views

How can I completely ban usage of some functions in output and mandate use of others?

For example, I hate that Mathematica uses Pochhammer symbol in outputs and prefer all the expressions in Gamma function. How can ...
4
votes
1answer
130 views

Tweaking Prime[n] to return 1 when n==0

I manually evaluate this cell to set Prime[0] Unprotect[Prime] Prime[0] = 1 Protect[Prime] I manually evaluate this cell to reset Prime[0] ...
14
votes
2answers
336 views

How to make use of NumericQ[x] = True (and use it safely)?

Basic Issue: I'm trying to understand the proper use of NumericQ's "magical" capabilities. Please consider the examples below. Actual question and some links are ...
1
vote
1answer
232 views
15
votes
1answer
304 views

Polynomial expectations of generic distributions

Summary Polynomial expectations depend only moments and cross moments of a multivariate distribution. I would like to use Expectation to compute polynomial ...
7
votes
2answers
190 views

Keywords to find documentation for this syntax

Mathematica allows this syntax, but I cannot find any documentation (or books) that discuss the various uses/advantages of it ...
18
votes
4answers
413 views

Function that caches when it returns unevaluated

How would you go about implementing a function that caches not the result but the fact that it didn't match a pattern? So that it doesn't waste time recomputing a complex time-consuming pattern ...
5
votes
1answer
232 views

Parts of Module body evaluated in external scope?

I have an expression that suggests that some expressions in a module body are dragging in definitions from outside the scope in a surprising way. First, consider a symbolic constant, ...
10
votes
3answers
344 views

How can I hold UpValues but evaluate other expressions?

Consider these definitions: own = "OwnValue"; down[_] = "DownValue"; sub[_][_] = "SubValue"; N[n] = 3.14; _[___, up, ___] ^= "UpValue"; The attribute ...
6
votes
1answer
425 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 ...
3
votes
2answers
114 views

Turning evaluation off

I am making a directed graph, but Mathematica keeps trying to evaluate my labels. I know that I can just use " ", but I have a lot of input. Is there a way to turn evaluation off? ...
2
votes
1answer
3k views

setting a variable equal to the output of FindRoot

So I set a function f[x] f[x_] := x*E^(-x) - 0.16064 Then I set a variable 'actualroot' to the function FindRoot, starting at 3 ...
15
votes
4answers
609 views

Recovering intermediate results from a Table after an interruption

I am interested in knowing if it is possible to recover intermediate results from a Table after an interruption. Let us say I want to produce a really useful table ...
3
votes
3answers
498 views

Help on evaluation control?

I want to plot series of slopes: x, 2x, 3x, 4x, 5x, 6x... I'm trying to do this: ...
6
votes
2answers
573 views

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

Let us say I want to show how the Taylor's series for Sin behaves: ...
8
votes
2answers
351 views

Why do I have to put Evaluate[] here

I wanted to draw some contours. I succeeded with this: ...
5
votes
3answers
284 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 ...
16
votes
1answer
545 views

Wagner's trick to monitor FindRoot no longer works in Mathematica version 8

I recently learned that we can use Print as a monitoring tool. My favorite is Ted Ersek's example ...
9
votes
4answers
225 views

Leave expression tree formatting the same when a replacement rule is applied

If I type e1 := 3 x + 2 (1 + y) z // TreeForm, I get an expression tree. If I then type e1 /. x -> 3, I get another ...
3
votes
1answer
152 views

Set promotes Rule to RuleDelayed?

In mentally building a model of how Mathematica works, I naively expected Set to create a Rule in a symbol's ...
0
votes
1answer
118 views

NIntegrate failling on floating value

I'm trying to take the following integral NIntegrate[ ((Sin[Q 1]-Q 1*Cos[Q 1])/(Q 1)^3)^2 * S[Q,0.4,2] * Q BesselJ[0,0.5Q] , {Q,0,Infinity}] ...
11
votes
3answers
266 views

Numbers in alternate bases transcend the evaluator?

It looks to me like a number in a base other than base 10 gets evaluated before the evaluator ever gets a chance to be tweaked. For example, FullForm[16^^abcdef] ...
7
votes
2answers
179 views

“A number in base b” and pure functions: why doesn't b^^# & work?

Why do the following not work (in Mathematica 7)? 2^^ # & /@ {1000, 1101} and 2^^ # & @ 1101 This does work: ...
12
votes
5answers
1k views

How to determine how much of a table is generated?

If I'm generating a table from a slow function, like this: foo = Table[SuperSlowExpression, {1000}] is there a way to determine after submission (so it is too ...
6
votes
2answers
507 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 ...
4
votes
1answer
218 views

Assumptions seem not to be considered

In the following a,b is a probability distribution, i.e. a+b==1 with ...
11
votes
7answers
329 views

Question about evaluation control

I want to make a function that takes a function as a parameter and prints an integral with the function inside. I've tried this: ...
17
votes
3answers
986 views

Asynchronous evaluation: Is it possible?

Currently we have a limited number of ways to perform asynchronous evaluation. The most common is through Dynamic and ...
7
votes
4answers
430 views

Attaching persistent assumptions to symbol definition

Is it possible to attach assumptions to a symbol? This relates to this question. Most of my work involves physical equations, i.e. there are basic assumptions on variables that will always hold true ...
7
votes
4answers
5k views

Mapping multiple parameters of a function to specific values

I am a little bit confused by the documentation for Apply (@@). I want to define a list of parameters, for instance: ...
5
votes
2answers
750 views

Speeding up mathematica by subsitituting numerical values

According to this Wolfram Blog post, one can speed up Mathematica code by substituting numerical values as soon as possible. How does one substitute before the main expression is evaluated? The ...
9
votes
2answers
160 views

A notebook created on demand from a main document showing executable input along with output cells

I would like to make Mathematica documents with hidden calculations, such that they can be visualized on demand. In general it can be done in several forms and I actually use some. I would like to ask ...
11
votes
2answers
279 views

Make a button that evaluates a function over and over

I would like to have a command "RedoButton" which would make a button (or whatever control is suitable) that when clicked would print the value of a certain function over and over in the same place. ...
10
votes
2answers
325 views

Unexpected differences with various uses of NormFunction

I would expect all of the following to give the same answer (2.12467) but only half of them give this answer. The others seem to be using the default ...
4
votes
1answer
422 views

Can a Table iterator “leak” into a Module?

I want to repeatedly call a module by using a Table statement. When I use an i iterator in the Table command calling the module, I receive the error message ...
10
votes
1answer
431 views

Manipulate evaluation sequence

Manipulate doesn't always evaluate in the order I expect it to. What is the evaluation sequence for Manipulate and other ...
3
votes
1answer
276 views

FunctionInterpolation Errors / Question re Evaluation Order and Options

I have using Mathematica functions that takes a Cartesian coordinate relative to the Earth (xyz) and converts it to a latitude, longitude, and altitude (lla). And here it is: ...
8
votes
4answers
1k views

Force function to make assumptions about its input variables in Mathematica

I'm trying to force a Mathematica function to make an assumption about its input variables. In my case, I'm trying to define a function to return the pdf of a Gaussian. But let's use a simple toy ...
5
votes
2answers
732 views

Expression evaluation inside of FindRoot inside a Compiled Function

I'm trying to get some performance increase out of my own implicit differential equation solver using Compile[]. The uncompiled function is of the following form: ...
7
votes
1answer
206 views

Difficulty catching thrown errors in asynchronous tasks

In this Question, Leonid explained that module variables can get garbage collected from a chain of asynchronous tasks unless their Temporary attribute is cleared ...