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

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2
votes
1answer
104 views

Defer parts of the expression

Is there a way to Defer only parts of the expression? For example, I have a=1; and then I want the expression to be shown as...
2
votes
1answer
212 views

Wrapping at evaluation for inline cell

I've been playing with inline evaluation and I've came to the conclusion that it's most convenient to put the Dynamic@ inside the inline cell, so I've started to ...
2
votes
2answers
84 views

Can I have Mathematica show intermediate forms before final evaluation?

If I have x = 2 and I want to evaluate y = x^2 I would like to the output to show ...
2
votes
1answer
114 views

Manual CellGrouping option causes crash at cell evaluation

Update: Try to reproduce this behaviour with CellGrouping set to manual. To do that: either evaluate ...
2
votes
1answer
310 views

Why is this expression being held, and how can I evaluate it?

I can't figure out why an expression isn't evaluating, even though there's no Hold* in its FullForm: ...
2
votes
1answer
9k views

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 ...
2
votes
1answer
455 views

Evaluate Numerator and Denominator Separately

I have this function. ...
2
votes
3answers
160 views

Function to preserve evaluation on display?

I'm looking for a function that applies the following behavior to an expression: -When the expression is given as the full input, or as part of a function that cannot be evaluated, it remains in ...
2
votes
1answer
55 views

recursively structuring a multivariate numerical optimization

Suppose that I want to partition the unit interval [0..1] into four subintervals whose max length is as short as possible. I can ask Mathematica to: ...
2
votes
2answers
170 views

Why does Mathematica not evaluate the difference recurrence using `RSolve` or `RecurrenceTable`?

Mathematica does not evaluate the following recurrence of two variables using RSolve and only echoes the input: ...
2
votes
2answers
169 views

How can I partially evaluate a function?

I have a multivariable function, from which I'd like to define a marginalization: f(a,b,c,d,...,z) ---> g(a,1,c,d,...,z) Generally, g will have fewer argument than f, possibly none (full evaluation)....
2
votes
1answer
91 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: ...
2
votes
2answers
181 views

How to apply list of values to a list of functions

I have the following: first= {1+a,2+a,3+a,4+a} and a list t={0,1,2,3} I want to evaluate the first element of "first" at ...
2
votes
1answer
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 ...
2
votes
1answer
110 views

How to explain the behavior of Rule inside these functions [duplicate]

I'm trying to define a function that takes an expression and spits out a pure function involving a replacement rule of that function's variable. An example would be a function ...
2
votes
1answer
262 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, -1}}]...
2
votes
3answers
446 views

GraphPlot only working when I evaluate twice

I have some code that builds a graph and some vertex coordinates, but when I evaluate it I get a message that the list of coordinates is not valid and the graph is not valid and it shows the output as ...
2
votes
1answer
34 views

Delete Cell Inside of Module

I want to print a dynamic output while some code is running and then automatically delete it when when the output is done. PrintTemporary is not quite what I am looking for -- I want the output to be ...
2
votes
1answer
78 views

Help on order of evaluation within plot function

it is my first time asking a question here so please let me know if there's anything I should be doing that I'm unaware of. I'm sure the answer to my question already exists on the site but I'm having ...
2
votes
1answer
70 views

Create a notebook and save it without prompting Dynamics

This is closely related to the recent: Creating self destructing notebook. However the answer doesn't work in my case. ...
2
votes
1answer
104 views

Clearing a global variable from inside a Module

This is a highly simplified version of a initialization problem I have with a complicated program with many (about 100) modules. If one enters: X=42; Clear[X]; the ...
2
votes
2answers
73 views

How can I use an InputField value as a variable name to save to?

I'm trying to save some settings and results from Manipulate, and I want to be able to save them to different variable names. The code I have is something like <...
2
votes
1answer
113 views
2
votes
3answers
59 views

Display a part of a notebook when MMA has done evaluating it

When you evaluate a notebook, it begins to slide upward and shows you a different part of your code, several cells upstream of the notebook... I was wondering if there is a command that could always ...
2
votes
1answer
281 views

How to abort running evaluation?

I would like to implement a "Stop" Button into a program that basically consists of a loop. Unfortunately I do not how to interrupt the running evaluation. Minimal Example: ...
2
votes
1answer
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... ...
2
votes
1answer
78 views

Inactive derivative: extract constants

I have a problem with an unevaluated derivative. In the example code below, i need the integration wrt to y be evaluated, while the differentation wrt x needs to stay unevaluated. I see the point that ...
2
votes
2answers
87 views

Order of Evaluate for Map

I would like to get a list of variable names as strings. For example, x = 1; y = 2; Map[SymbolName, Unevaluated /@ Unevaluated@{x, y}] {"x", "y"} This works ...
2
votes
1answer
152 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 ...
2
votes
1answer
41 views

is there a way to construct a pattern that would trigger when an expression is used as a held/unevaluated in some form?

For example, consider the following code f[x_] := (Print["evaluated f"]; workWith[x]); We use it, then f evaluates: ...
2
votes
2answers
2k views

Integrating a Simple Piecewise Function

If I define f[x_]:=If[x<0,-1,1] and then integrate,say Integrate[f[x],{x,-3,7}] I get what I expect, namely 4. But ...
2
votes
1answer
124 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 ...
2
votes
2answers
248 views

Generating an editable table that can be used as input

Say I have a number $n_{max}$. I want a command to generate a table like 1 1 2 2 3 3 4 4 ... nmax nmax where the second column is editable, and this table can be ...
2
votes
1answer
146 views

Need help looping a notebook evaluation

I'm a new user and would like to find the minimum value of soln1[30] obtained after repeating the following evaluation (below) for 1000 cycles (for instance). I can obtain sequential values of soln[...
2
votes
1answer
189 views

Differentiating a function that has NIntegrate within it

I am something of a novice with Mathematica. I have written the following code; ...
2
votes
1answer
219 views

Evaluation of the second argument to NIntegrate

The expression Integrate[x^2, Flatten[{{x},{1,2}}]] evaluates properly, to $\frac{7}{3}$. However, ...
2
votes
1answer
64 views

Label cell goes away with SelectionEvaluate

When a given cell has a label (given with the CellLabel->"label" option of the cell), then this label disappears after calling SelectionEvaluate[ nb ] when the ...
2
votes
1answer
372 views

Dynamic [ NotebookEvaluate [“_”] ]

A nice way to centralize various tasks in one notebook is the NotebookEvaluation function. For instance I can evaluate ten notebooks from a single notebook (e.g. ...
2
votes
1answer
168 views

Reuse local variable in declaration within With [duplicate]

Considering the richness of Mathematica.SE, I am quite surprised I could not find my answer... I am very sorry if it is a duplicate. Consider the following example: ...
2
votes
1answer
150 views

NotebookWrite undo

Is there way to make NotebookWrites undooable? For example let's say I open a new notebook and then run. ...
2
votes
1answer
50 views

Recognition Power Head for numeric value

We know: Map[Head, {a, a^2, a^3}] (* {Symbol, Power, Power} *) and Map[Head, {2, 2^2, 2^3}] all of them will be known as <...
2
votes
1answer
121 views

How to properly define this function of function

I encountered real problem at first, and here is the toy example variable argument stored some expression that is generated from other parts of the program. I ...
2
votes
1answer
73 views

Non-autonomous Dynamical system Sliding mode controller Error

This code is a simulation of a sliding mode controller of a non-autonomous dynamic. When I use ArcTan in input, I receive an error. ...
2
votes
1answer
81 views

Failure in the use of FullSimplify

My question is about an apparent failure of the function "FullSimplify" to simplify an easy algebraic expression. This is the expression that I ask Mathematica to evaluate: ...
2
votes
1answer
110 views

Why isn't Table iterator value inserted in failed NIntegrate arguments?

Consider this simplest example: Table[{z, NIntegrate[f[x], {x, 0, z}]}, {z, {1}}] Here f is not defined, so ...
2
votes
1answer
112 views

What is “ (Dialog) Input [ ] := ” after evaluating a cell?

I have done a time-consuming run and calculation. After many hours ( about 7 hours!), the black color which shows that the cell is evaluating, turn into gray and a strange text appears like this : <...
2
votes
1answer
247 views

Piecewise function with user-input interval

I would like define a function g[data,bins,x] which is a piecewise constant function taking value data[[i]] in the range ...
2
votes
1answer
73 views

Evaluate only one from a set of procedures

Let's say I've got a list of procedures: {Print[1];, Print[2];, Print[3];} And I want to only evaluate 3rd one: ...
2
votes
1answer
136 views

Implementing a For (?) or series or loop (?) for individual results for every x to n

I'm working on improving a modeling formula and have spreadsheets worth of data to use, but my work so far has been quite tedious. I'm essentially pulling 20 rows of data from each separate sheet of a ...
2
votes
1answer
325 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 ...