Questions about how Mathematica evaluates expressions, tracing evaluation (Trace*), handling expressions in unevaluated form (Hold*, Unevaluated), nonstandard evaluation, etc.
12
votes
1answer
222 views
Using Evaluate and Evaluated -> True in Plot
A few use cases:
(1) This, as expected, returns (almost) immediately:
f[x_?NumericQ] := Evaluate[(Pause[1]; x)]
Plot[f[x], {x, 0, 1}]
(2) This takes ...
0
votes
1answer
62 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.
11
votes
2answers
212 views
can a ColorFunction have side effects?
Can anyone explain this (to me) odd behavior. If I run this code once (fresh kernel) it works as intended.
...
9
votes
4answers
192 views
How are parameters evaluated for a Plot in Manipulate
I am trying to get my head around how Manipulate evaluates functions in a Plot. I have read the introduction to Manipulate, and introduction to Dynamic, but I still ...
1
vote
2answers
102 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
227 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 ...
7
votes
2answers
189 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 ...
10
votes
1answer
132 views
Evaluation indicator for a notebook
I have a GUI with a number of TabView and other Manipulate controls. Sometimes clicking from one Tabview to the other can take a while, and I would like to have a global "Please wait" indicator.
So ...
1
vote
2answers
82 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
76 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 ...
4
votes
1answer
120 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]
...
13
votes
2answers
222 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
107 views
Particular solutions of a Differential Equation not evaluated in a given case
Below first case which gives particular solutions of an OED correctly:
...
6
votes
2answers
147 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
...
13
votes
1answer
395 views
Unique[] symbol not properly tracked
In a nutshell, why does this work (change y and see how the value updates)
...
5
votes
1answer
179 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, ...
15
votes
1answer
194 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 ...
2
votes
2answers
595 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 ...
4
votes
3answers
312 views
All curves in plot have the same style. Cannot be fixed with Evaluate[]
Usually, when I plot multiple curves in Mathematica
Plot[{x,x^2,x^3},{x,0,1}]
they are given different colors. However, if I try to construct a list inside the ...
10
votes
3answers
226 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
187 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
85 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
391 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
...
11
votes
3answers
237 views
Returning an unevaluated expression with values substituted in
Let's say I have a function
formula[x_List] := (x[[1]] - x[[2]]) + (x[[3]] - x[[4]]);
and I want to pass it a variable and get back the unevaluated formula with ...
3
votes
3answers
233 views
Help on evaluation control?
I want to plot series of slopes:
x, 2x, 3x, 4x, 5x, 6x...
I'm trying to do this:
...
19
votes
2answers
632 views
Mathematica for Computer Scientists
Background
I've coded in C/Scheme for 10 years. I have a BS CS.
I've recently become very interested in pattern-matching (lisp's match macro), and term rewriting systems, which brought me to ...
9
votes
4answers
263 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
...
5
votes
2answers
216 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
178 views
5
votes
3answers
167 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 ...
15
votes
1answer
341 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
...
3
votes
1answer
108 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 ...
9
votes
4answers
169 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 ...
0
votes
1answer
92 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}]
...
7
votes
2answers
153 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:
...
6
votes
2answers
243 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
136 views
Assumptions seem not to be considered
In the following a,b is a probability distribution, i.e. a+b==1 with ...
10
votes
7answers
252 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:
...
6
votes
4answers
224 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 ...
10
votes
2answers
254 views
DSolve cannot solve for certain branches of the solution
Could somebody please tell me, why I am always getting an error message when trying to run the following code:
...
5
votes
2answers
167 views
Why doesn't Evaluate appear to work in this RegionPlot example with MatchQ?
I am trying to plot the region over which a function of two (real) parameters a and b is real-valued, using ...
3
votes
4answers
1k 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:
...
6
votes
2answers
419 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
106 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 ...
10
votes
2answers
176 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
256 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 ...
11
votes
3answers
204 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] ...
4
votes
1answer
245 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 ...
17
votes
3answers
396 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 ...
3
votes
1answer
166 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:
...
