Questions tagged [evaluation]
Questions about how Mathematica evaluates expressions, tracing evaluation (Trace*), handling expressions in unevaluated form (Hold*, Unevaluated), nonstandard evaluation, etc.
1,554
questions
5
votes
2
answers
245
views
Is it possible in Mathematica to get a step-by-step evaluation of the following?
Is it possible in Mathematica (or WolframAlpha["...]") to get a step-by-step evaluation of the following?
...
- 605
1
vote
0
answers
31
views
Monitor inside core function
I like DistanceMatrix: its performance is surprisingly high, even for a big data.
However, for a huge arrays and custom ...
- 1,197
0
votes
1
answer
60
views
1
vote
0
answers
54
views
Elliptic theta function wont evaluate [closed]
It appears that Mathematica wont evaluate the Jacobi theta functions when the last argument has a magnitude greater than 1, for example: EllipticTheta[1, 1.5, 0.9] ...
- 151
1
vote
2
answers
80
views
SortBy does not work correctly when nest in Evaluate in With in Block
I have got some formula in Mathematica, then I want to pass value to verify them.
full code
...
- 197
2
votes
3
answers
163
views
0
votes
2
answers
74
views
Same code behaves differently as a pure function and a function, and insider another function
I have a rule-transformer that takes a list of rules (and a list generator = {σ[z], σ[-1], σ[1]})
...
- 513
2
votes
1
answer
48
views
How to apply a transformation to a total derivative?
I want to transform total derivatives into normal derivatives:
Dt[r, t] == -r*Dt[v, x] - v*Dt[r, x] /. Dt[f_, s_] :> D[f[x, t], s]
To get:
...
- 363
2
votes
1
answer
97
views
How to force evaluation of RuleDelayed?
(I'm not sure if the title of this question is appropriate, sorry!)
After defining selfApply function that resolves the mutual references contained in Association, I wrote the following code:
...
- 93
3
votes
4
answers
363
views
Eigenvectors are divided by zero depending on evaluation, 6x6 matrix
I calculated the Eigenvectors of the $6\times 6$ matrix $m$ with parameters $(a,b,c,d,e,f)\in \mathbb{R_{\ge 0}}$. If I set e.g. $b\rightarrow 0$ after calculation, then 4 of the 6 Eigenvectors are ...
- 563
4
votes
3
answers
434
views
Eigenvectors are divided by zero depending on evaluation, 4x4 matrix
I calculated the Eigenvectors of the $4\times 4$ matrix $m$ with parameters $(a,b,c,d)\in \mathbb{R_{\ge 0}}$. If I set e.g. $b\rightarrow 0$ after calculation, then some of the Eigenvectors are ...
- 563
0
votes
1
answer
46
views
Evaluation gives different results before and after simplifying expression
I am trying to evaluate $h(z)=\frac{f(z)}{g(z)}$ at points $z$ close to 0. Here I have taken an example value of $z=\texttt{z1}=10^{-7}$ for demonstration. I notice that evaluating the fraction before ...
- 121
2
votes
2
answers
85
views
How to prevent evaluation without simplification?
I am trying to compute a sequence of terms, which have a form similar to $g(z)$ at different points $z$. For $z$ close to 0, I have observed that the terms are evaluated as 0/0 (indeterminate form) ...
- 121
0
votes
0
answers
47
views
Passing an unevaluated test
I want to write a function (in a package) that takes a boolean test as an option. Here's a toy example to illustrate what I have in mind:
...
- 19.5k
1
vote
1
answer
143
views
Newton Raphson 0th order with gauss elimination error
I'm trying to do a Newthon Raphson with 1st order continuation to solve a problem with 4 variables (fix 2 and obtain the results of 2 (x and Chi).
...
1
vote
1
answer
57
views
`FindMinimum` can't evaluate `Nearest` numerically
I'm trying to use Nearest as a function to minimize over: a toy example is
...
- 3,897
0
votes
0
answers
59
views
Automatic evaluation of a function for variable values defined from different data tables in the attachments
I want to evaluate a function whose variable values are defined in different data files. I want to know that how can I write code such that when the function's evaluation is exhausted for one table, ...
- 361
0
votes
0
answers
42
views
How to find a positive minimum of a function?
How can I find a positive minimum of f and its corresponding R0?
...
- 379
1
vote
1
answer
38
views
How to clear all definitions/symbols declared in all sections with the given tag?
Consider a list of chapters/sections etc. that have the same tag, say, "evaluation". Could you please tell me how to clear all the functions/symbols/definitions etc. that have been defined ...
- 4,642
0
votes
0
answers
19
views
Writing Files In NMinimize - Variables Not Evaluating
I am trying to use minimization with an external process. To do this I need to write a file to be used as input for the external process. However, when a function that writes a value to file is called ...
- 5,063
0
votes
0
answers
31
views
Key Command for "Evaluation -> Quit Kernel -> Local" on Mac
I have an accidental run away loop in some code and Wolfram Desktop 13 is frozen. Usually when this happens I simply execute "Evaluation -> Quit Kernel -> Local". This time however its ...
1
vote
0
answers
75
views
Problem with the Manipulate command
I am trying to upload a notebook with the following code to my blog, but every time I upload it, the "manipulate" code does not give anything. Do I have to change anything?
...
6
votes
2
answers
186
views
Listing all user-defined definitions used in a function call
Is it possible to obtain all user defined definitions (and attributes) that are used in the evaluation of certain command (or alternatively just their symbols which I could imagine being easier when ...
- 4,197
0
votes
1
answer
73
views
1
vote
1
answer
74
views
Unwanted reevaluation in Manipulate with RandomPointConfiguration
Here is a simple illustration of a problem I am encountering. I want to use RandomPointConfiguration inside Manipulate, but it ...
- 548
2
votes
0
answers
26
views
Silly question about holding an expression in a sum [duplicate]
Sorry about this dumb question in advance. Suppose I evaluate this :
test[x_, y_] := Laplacian[x^2 + y^2, {x, y}]
test[x, y] /. {x -> 1, y -> 1} (*4*)
Now if ...
- 506
0
votes
0
answers
29
views
Keep specific case of function unevaluated until defined while general case is defined
I'm solving a particular differential equation and I have the Laplace transform of y[t], Y[s]. Naturally, my next step is y[t_]=InverseLaplaceTransform[Y[s],s,t].
...
- 183
5
votes
2
answers
159
views
How can I make Table of Defer[Sqrt[3i] - k Sqrt[3j]]?
I am trying to make a Table of expressions Defer[Sqrt[3i] + 2 Sqrt[3j]], e.g
...
- 1,000
1
vote
0
answers
51
views
Evaluate all If branches [duplicate]
In Mathematica, I have the following code:
f1[x_] := 1;
f2[x_] := 2;
f[x_] := If[x > 5, f1[x], If[x < 0, f2[x], 3]]
f[x]
Which produces the following output:...
- 275
1
vote
1
answer
62
views
Why doesn't Sequence@@ work inside Manipulate[]?
I'm trying to use Manipulate[] and I need to have a non-fixed amount of sliders.
I tried writing something like:
...
- 13
4
votes
1
answer
106
views
How to evaluate expression completely?
In MMA 13.2, if we run
Quantity[1, 1/"DegreesCelsius"]
it automatically throw a message
But if we run
...
- 16.9k
-2
votes
1
answer
66
views
How to make faster of a code containing more iteration point? [closed]
I am trying to evaluate a code of the Power Series Solution method to get the results. Also, the time of evaluation depends on the parameters I am using. When the iteration point is 50, 60, or 80, it ...
0
votes
1
answer
64
views
Code doesn't stop running - how to fix Part::partw? [closed]
I have this code divided into two notebooks, the first notebook is running just fine, and It gives some information that the second notebook uses, like some variables. The second notebook exhibits the ...
0
votes
0
answers
41
views
How can I suppress the multiple redrawing of Manipulate charts every time, on every evaluation after editing code....?
How can I suppress the multiple redrawing of Manipulate charts every time, on every evaluation after editing code.... After coding a few lines, and evaluating I end up having many many Manipulate ...
- 21
1
vote
0
answers
44
views
Avoiding NDSolve symbolic calculation
I'm trying to solve the following differential equation, involving a nonlinear ff2 (discrete) function ; however, something goes wrong, as NDSolve tries to compute ff2 symbolically.
...
- 11
2
votes
3
answers
107
views
SetDelayed assignment not producing expected result when using ReplaceAll
In Mathematica, I am surprised that the following code does not do what I expect (what I expect is in comments after each evaluation). The problem seems to be due to the fact that when I define test ...
- 269
1
vote
1
answer
47
views
Unable to evaluate integral in DSolve solution
I define the PDE
PDE1 = \[Rho] G[q, w] - (\[Rho] w + S - q) D[G[q, w], {w, 1}] - \[Mu] q D[G[q, w], {q, 1}]
which Mathematica is able to solve in terms of an ...
- 155
2
votes
3
answers
196
views
A simple question about syntax: how to shorten [email protected]@
Consider the following function:
...
- 4,642
5
votes
0
answers
84
views
Using Cases to select expressions from a list
I am using v12.2.0 on Win7-x64. I want to use Cases to select the Times and Plus cases from ...
- 41.7k
1
vote
1
answer
49
views
A problem with the evaluation of expressions using assumptions through Mathematica
I want to evaluate the expression below,
$((2 (a_{01}+2 ya_{02}+x a_{11})^2+(b_{01}+2 y b_{02}+x b_{11})^2) (2 (a_{10}+y a_{11}+2 x a_{20})^2+(b_{10}+y b_{11}+2 x b_{20})^2))$,
at $x=-((2 (2 a_{02}a_{...
- 179
2
votes
1
answer
174
views
Can one use Break inside Switch?
The documentation for Switch states that "You can use Break, Return, and ...
- 126
0
votes
1
answer
79
views
Dealing with exponents that contain units?
Many of the equations I deal with involve powers of quantities which contain units. However, when the exponent contains units (e.g., ...
0
votes
1
answer
55
views
Evaluating an integral of geometric Brownian motion
I am a Mathematica novice. For an operations research application, I am trying to work with the following wealth process in Mathematica,
$$
d W_t = (\rho W_t + P_t) dt\ ,
$$
where $P_t$ is a stream ...
- 155
11
votes
2
answers
1k
views
What is a function?
Regarding:
Map[#[{2, b}] &, {Reverse}]
The above works, but it makes my head spin. The documentation for Map says that the ...
- 447
0
votes
1
answer
35
views
What is the relationship between a list of symbols created by a specific name, and a expression with such a name?
I'm trying to create a list of symbols called "x" for calculating symbolic gradients of some functions, so I write:
...
- 3
0
votes
1
answer
42
views
Expression for variance of a truncated distribution as a function of the point of truncation
I am working on a project where I need to calculate variance of a truncated distribution. Suppose $X$ has some distribution and $x\in\mathbb{R}$. I am interested in $var(X|X\leq x)$. Given some ...
- 143
1
vote
0
answers
29
views
Block the appearance of the dialog windows "The kernel is not responding to a Dynamic Evaluation" and "Abort Dynamic Evaluation" [duplicate]
I have high-demanding Mathematica task which uses a lot of CPU. Its evaluation is interrupted with two types of an annoying dialog window.
The first one is
"The kernel is not responding to a ...
- 4,642
1
vote
0
answers
94
views
Optimizing my code to solve nonlinear system
I have solved a non-linear system using Eliminate[] and Solve[], using a really nice answer found here I am able to use ...
0
votes
1
answer
72
views
Find solutions after using Eliminate
I have used Eliminate[] to reduce a system of equations as found here, I then proceeded to verify that indeed my system has zeros using this code. My question is, ...
1
vote
1
answer
85
views
The ultimate output control method
The ultimate substance of all matter is the atom, likewise,
the ultimate substance of mathematica cell is the cell expression,
and it can be obtained easily.
After copying the cell expression, and ...
- 4,047