# Tagged Questions

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

441 views

### Trying to calculate derivatives of spherical harmonics

I am trying to confirm what is shown on this website: http://functions.wolfram.com/Polynomials/SphericalHarmonicY/20/01/01/0001/ But when I type ...
353 views

### Using up-values and down-values

I have a problem I'm trying hard to find a solution for, although I don't know if a solution exists. The following rules produce the result e[2].f[] ...
40 views

### Evaluation order in polynomials

I'm confused by the evaluation order of polynomials containing division. Consider these two polynomials: (x^2 + y) z/w (1) a/b (2) And their tree ...
91 views

### Why doesn't my expression evaluate at the subkernel?

Consider this code: ...
72 views

### Evaluation control with TagSet

Suppose I have a property associated with two functions using TagSet: ...
61 views

### Why returning False? [closed]

Can anyone explain the false? I'm trying to grab co-efficient in front of X^2 I think. I say I think as I'm following my tutors example using his screenshot the only difference between his question ...
416 views

### Mathematica shift-enter problem [closed]

Would really appreciate if someone can help with this problem: When I first open a Mathematica note book, say you do 1+2 and press shift-enter. As expected, I get "3" as the output. Now suppose you ...
138 views

### Is this caused by round-off errors?

Let's consider this integration Integrate[ E^(4 n x s) (1 - x)^(-1 + 4 n μ) x^(-1 + 4 n ν), {x, 0, 1}] It returns ...
71 views

### Failed to use N[%] for a infinite series

I am trying to evaluate a infinite series: $$2 \sum _{l=1}^{\infty } \Re\left(n^{\frac{2 i \pi l}{\log (q)}} \Gamma \left(\alpha -\frac{2 i l \pi }{\log (q)}\right)\right)$$ With the code: ...
160 views

### Getting terms and only evaluate specific parts

I want to expand the expression but I do not want it to evaluate. Sum[(HoldForm[1/(2 # - 1) - 1/(2 # + 1)] &)[i], {i, 1, 6}] However if you evaluate this you ...
58 views

### Unknown Power showing up in Formula [closed]

I have the following worksheet below. (I took a screen shot because I didn't know how to type the code for the particular function). Circled in red are powers that shouldn't be there and yet ...
192 views

### How to understand the difference between Sqrt and Log after ClearAll them

I came across this post, here I change the last line of the code Unprotect[Sqrt]; Sqrt[x_] = "blahblah"; Protect[Sqrt]; Sqrt[2] "blahblah" ...
580 views

### How to NOT simplify fraction

How can I prevent Mathematica from simplifying fractions? What I would like to do is run a test on a list of fractions to see how many are in their reduced form. For example, I have a list: ...
1k views

### What happens when you divide by ##?

I've been playing around with sequences a bit. In particular with using ## with unary and binary operators. Let's start simple, the following all make some kind of ...
93 views

### Trying to Simplify an Expression

I'm trying to simplify an expression: ...
243 views

### Associativity of /@ [duplicate]

Why are the following not equivalent: Map[Line, Map[(Print[#]; #) &, {{{2, 1}, {1, 1}}, {{-2, 1}, {3, 1}}}]] which produces ...
125 views

### Why does Rule behave like this?

Why does {x, x^2, x^3, a, b} /. x^n_ -> f[n] result in {x, f[2], f[3], a, b} when ...
363 views

### Expanding huge expressions that simplify and factor

The following is for Mathematica 8.0.4 running on Windows 7 laptop (6GB memory). I have eight expressions that are unexpanded multivariate polynomials in 6 variables. They are huge expressions, so ...
89 views

### Return the incomming expression on false

when I have an expression, that is unknown to mathematica, it is returned exactly the same, as it was called. For example SeeFlyingPigs[1,2] called on the line ...
188 views

### Can I define an axiomatic (Boolean algebra) system and prove theorems using Mathematica?

The general question is Can I define an axiomatic system and prove theorems using Mathematica? The more concrete one is about Boolean algebra. I consider this axiomatic Boolean algebra system (...
75 views

### Package function not evaluating

I have a short package like this: ...
136 views

### ReplacePart equivalent for Associations

I have a fairly complicated Association. I wish to use/create a function such as ReplacePart to operate on certain Keys within this multi-level Association. Here's ...
81 views

### Aborting from a Dialog box

I'm trying to abort a While cycle, with a dialog box. I've tried the following: ...
361 views

### What does f_[whoCalled]^:=f really mean?

I came across the following post by John Doty in this Google Groups discussion: On Friday, January 11, 2013 8:23:16 PM UTC-7, amzoti wrote: It is clear the Mathematica uses Lisp as one ...
56 views

### Evaluating Expectation [duplicate]

I would like to have a result equal to a function : ...
160 views

### Integration with mathematica? [closed]

I am very new to Mathematica. I am trying to evaluate ∫ (1+lnx)Sqrt(1+(xlnx)^2) using Mathematica. I know a substitution must be done so I have set ...
148 views

### Mathematica displays the unevaluated expression Expectation function

The evaluation runs for a few seconds and then Mathematica displays the unevaluated expression Expectation function ...
308 views

### Difference between Evaluation>>Quit Kernel and Quit[]

What is the difference between Evaluation >> QuitKernel and Quit[]? Both seem to quit the kernel (and clearing all ...
497 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., ...
83 views

### Regarding Evaluated True

Done a bit of reading: Normal[Series[ ]] does not give a normal expression Regarding the Evaluated->True, consider: ...
66 views

I want to Abort[] an evaluation without generating this message: $Aborted Is there a way to do this? This messages modifies my notebook, and I don't want this to ... 0answers 71 views ###$Epilog does not work when exit

The following code does work: \$Epilog := Print@1; Quit[]; But if I close the document and exit WM or click QuitKernel, it does not work. Why?
40 views

### Why does the same function defined by Set and SetDelayed look different? [duplicate]

I start with the following input: f[n_] = Sum[(1+x)^j, {j,1,n}]; g[n_] := Sum[(1+x)^j, {j,1,n}] When I try to evaluate the code above I get: ...
166 views

### How to determine how much time it will take to finish a cell expression?

I am trying to integrate a large matrix with elements that contain trigonometric expressions. The evaluation is taking a long time--4 days, and it is still running. Is there anything I can do to find ...
2k views

### A one line proof that one is zero using Mathematica 10

a = (Sqrt[2] + 1) (Sqrt[2] - 1) - 1; {a/a, Simplify[a]/a, b/b == Simplify[b]/b} {1, 0, True} This one line "proof" that ...
71 views

### Strange behavior of the Evaluate function

I am solving a system of differential equation whose unknown are saved under variable vec={C00,C01,C10,C11} and the solutions are saved under variable ...
57 views

### Is it possible to pipe the output of EvaluationMonitor to Excel?

I have an EvaluationMonitor setup to capture the points processed by NIntegrate. This is a case where the same function, integrated over the same region in cartesian coordinates yields a dramatically ...
101 views

### Slowdown of Flat attributed function

I was trying to write an associative function f using the attribute Flat. ...
285 views

### Dynamic and Refresh

If I am not mislead by my memory, in Mathematica 6 a function Refresh was introduced, having the options UpdateInterval and <...
128 views

### Defining a function that prints both the name and value of a variable defined locally within the calling function

To save time when debugging with Print statements, I'd like to define a function -- call it PrintVal -- that prints both the name and value of a variable defined locally within the calling function. ...
348 views

### Why does the documentation call functions “pure”?

Clearly, functions in mathematica are not pure functions according to the definition on Wikipedia (no side effects - basically implementabe with table lookups): ...
68 views

### Is there a simple function identify the sign of an expression given constraints

I'm looking to find a simple function that can identify the sign of an expression given a set of constraints. I have looked around and do see that there is a few threads on this but I'm not sure I ...
51 views

### How can I get numerical answers to integrals involving the error function?

This is the integral I am trying to evaluate in mathematica: Integrate[Exp[-p^2/(m w h)], {p, -Infinity, Sqrt[h m w]}] Can someone show me how to get a numerical answer out of this?
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] ...
90 views

### Assigning to the “local” version of a symbol

Compare Manipulate[c[1] = 1; c[1], {c[1], 0, 1}] with Manipulate[Do[c[i] = 1, {i, 1}]; c[1], {c[1], 0, 1}] The first case ...
122 views

### Strange integration

Bug introduced in 9.0 or earlier and fixed in 10.1 Note: Beginning with V10.1, this integral returns unevaluated but without error messages. I tried to evaluate this line ...
71 views

### A problem about sorting final result

Three days ago, I asked a question about B-Spline Basis fuction here @Michael E2 given a solution to make the order of interval looks normal The easiest way would be to sort it afterwards: MapAt[...
98 views

### How can I set a RadioButton to invoke an action, like a Button can?

In Mathematica one can create a Button which, when clicked, invokes an action. For example... ...