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

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Strange integration

I tried to evaluate this line Integrate[((-I/2) (E^((-I) x) - E^(I x)) + ((E^((-I) x) + E^(I x)) x)/ 2)/((-1 + E^x) x), {x, 0, Infinity}] Then I get $14$ ...
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2answers
70 views

Pattern matching to head with HoldFirst

I want to define a function that only operates on expressions with a head from a given list, such as f[expr:(_And|_Or)] := Print["LHS is ", expr[[1]]]; This of ...
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2answers
82 views

Extract the real components from a very large expression

Suppose I have a very long expression (>500,000 characters) which contains a mixture of real and imaginary terms. e.g ...
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44 views

Cell seems to be evaluating in exponential time even though it shouldn't

I am trying to implement Newton's method for a given function f[x] and a starting x-value xval. The code should print out each new x-value as it approaches one of the zeroes of the functions. g[x] is ...
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131 views
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Evaluate an expression at a specific point

In Maple, you right click and can evaluate an expression (whatever it is) at a specific point say: Expr.= abcddafjosjfoj, then right click and simply evaluate at c=-34 say. But how does one do the ...
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194 views

Confused about Unevaluated

Why does Map[Unevaluated, Table[PauliMatrix[i], {i, 1, 3}] give {Unevaluated[{{0, 1}, {1, 0}}], Unevaluated[{{0, -I}, {I, 0}}], Unevaluated[{{1, 0}, {0, ...
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159 views

direct assignment to the element in a Table

I have already asked a related question here why set values in this way doesn't work? But I think I have to write the question which I encountered explicitly? ...
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28 views

How to get Mathematica to abort the current evaluation if an assertion fails?

I can turn on assertions, but they don't terminate the current evaluation. For example: ...
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37 views

GCD of Table entries

This question is from a newbie, so please be gentle in thrashing if I'm missing something very basic. How can I use GCD on a matrix/vector entries stored as Table. For example, if ...
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33 views

Replace symbols in output without evaluation

I found the Wolfram example for ExpandNCM but I want a more human-readable output form. I want to evaluate ExpandNCM, for example with ...
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87 views

Working with derivative of conjugate of a complex number

I have a complex function, lets say $g(x)$. I want to take its and its conjugate's derivative. I need the solution of derivative which must be symbolically and computationally efficient. Lets take an ...
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3answers
147 views

How can I make a summary of all the commands of Mathematica?

I would like to have a simple way to get summary information about all the many commands built into Mathematica. How could I do this? Is there a site I may refer to?
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57 views

How to make strong assumptions?

Or put in another way, how to make a variable behave as it belongs to a specific domain, even outside the use of simplify or other commands alike? For example: ...
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65 views

How to evaluate some parts of an expression inside Hold? [duplicate]

I want to return a Hold expression but with some parts pre-evaluated. The easiest way to explain this is probably through code example. Here is what I have ...
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37 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 ...
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2answers
57 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 ...
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1answer
121 views

Generate conditions seems to not work [closed]

I am trying to compute the following integral Integrate[E^(I*k*Omega*t), {t,0,T}, GenerateConditions->True] for which Mathematica returns ...
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2answers
346 views

Converting expression into string without evaluating it

How can one convert a Mathematica expression into a string without the expression being evaluated first? I tried using Hold, but it returns ...
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1answer
116 views

Caching data in Mathematica package

Consider the following: m=Quantity[1,"meter"] If I run the package, it will return 1m But when I load the package, the ...
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2answers
152 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 ...
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1answer
44 views

How do you programmatically update a tag using the TaggingRules mechanism?

Consider the following simple front-end code: ...
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1answer
70 views

How to Reap data from a ScheduledTask?

Here is an amusing little function mapped over a range just to iterate it. It ignores its argument and works entirely by side-effecting a global variable: ...
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1answer
51 views

How can I force an installed, user-created palette to automatically evaluate?

I have created a palette in Mathematica v10.0.2, and used the Menu-->Palettes-->Install Palette functionality to successfully install it. When I choose my palette (from the dropdown menu), rather ...
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1answer
68 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 ...
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2answers
82 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 ...
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40 views

Package function not evaluating

I have a short package like this: ...
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1answer
56 views

Aborting from a Dialog box

I'm trying to abort a While cycle, with a dialog box. I've tried the following: ...
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1answer
50 views

How to abort silently?

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 ...
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35 views

Expand Expression with Nested Special Functions [closed]

I am trying to study the following sequence for $a=1$, $n \ge 1$: $$\alpha_n=(1-aq^{2n})\sum_{j=0}^{n}\frac{(aq;q)_{n+j-1}(-1)^{n-j}q^{\binom{n-j}{2}}}{(q;q)_{n-j}(q;q)_j^3}$$ using Mathematica, where ...
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66 views

Commutative algebra by generators and quadratic relations

My apologies if this has been asked before. Please also be gentle, as this is my first question here. I am trying to define a commutative algebra by generators and relations in the following way. ...
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88 views

How to extract a variable names (not values) from a list of transformation rules?

I am trying to extract variable names from a list of transformation rules mapping = {var1 -> 'val1', var2 -> 'val2' }. Variables ...
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1answer
146 views

Evaluation of second argument to NIntegrate

Apologies if this is a duplicate, but I couldn't find it. The expression Integrate[x^2, Flatten[{{x},{1,2}}]] evaluates properly, to $\frac{7}{3}$. However, ...
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41 views

Output cell written with NotebookWrite dissappears on whole notebook evaluation, yet remains if I individually evaluate it

Create a new notebook with the following two input cells: NotebookWrite[EvaluationNotebook[], Cell[BoxData[ToBoxes[Manipulator[Dynamic[x]]]], "Output"]] and ...
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116 views

About evaluation in Block

I'm completely puzzled by the following codes: Clear[func, f] a = x^2 + z; func[k_] := Block[{f}, (f[x_] := Evaluate[(a /. {z -> k})]; f[1])] func[2] ...
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343 views

How to tell Mathematica not to simplify an expression

While there is this question with a very similar title, it does not answer my question, which is: I have part of an input, in my case Re[Exp[I*x]] which ...
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156 views

Evaluate code to some point

How can I evaluate my code, up to some point? I don't want to evaluate all of my code always. I have to use Shift - Enter for every line from the first cell up to the point I want to be, and it's not ...
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225 views

Skip one step of the loop if there is an NIntegrate::eincr message

Is there a possibility of skipping one step of a loop if in this step there appears an error like NIntegrate::eincr? After skipping, the loop should go to the next ...
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240 views

Particular solutions of a Differential Equation not evaluated in a given case

Below first case which gives particular solutions of an OED correctly: ...
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37 views

Unexpected order of evaluation in ForAll

I noticed that ForAll behaves rather unexpectedly when its first argument is a symbol which has been Set in an outer scope. For ...
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0answers
75 views

How can I use L.Shifrin s code formatter package better

in the document of HoldAllComplete, it says: Evaluate cannot be used to override HoldAllComplete.. for example, when I'm ...
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2answers
56 views

Coordinates of MeshPoints

The output of a set of differential equations solved with NDSolve produces a series of curves and I need to obtain the spacing between these curves at a given level ...
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0answers
83 views

Smart pointer for Mathematica?

Would the implementation of the smart pointer idea be possible in Mathematica ? Let's say I have an object "o" of the form Class[object] where object is an Association, and Class has the HoldFirst ...
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106 views

How to make a graph of this function?

I need to plot the following function: ...
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49 views

Getting Gamma as a result for integration [closed]

When finding the mean from the distribution, fx = 4*x^3*Exp[-x^4] meanx = Integrate[x*fx, {x, 0, Infinity}] I get Gamma[5/4] Could someone explain what ...
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42 views

Question on Function in Replacement Operation

I am trying to create a replacement function which, depending on the input, gives an additional minus. In my example I have an undefined function a with two ...
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80 views

Summing the probability distribution to 1 to convince myself

I have worked out a probability distribution and want to check its sum which is necessarily 1. First we write $$ r \triangleq \frac{(2 \lambda + \mu)^2}{2(\mu + \lambda)^2}, \quad s \triangleq ...
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53 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 ...
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78 views

How to implement nested With as a single construct using functional programming (Fold)?

It is possible to define my own With construct where each local constant can depend on the previous defined local constants? I wish to replace something like this ...
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102 views

Expression for evaluating multiple functions?

I am constructing 3D data points for a plot and corresponding to specific conditions "manually". I define the values of five parameters [these I always have to define myself]. From those, I evaluate ...