Questions tagged [syntax]
Questions on the correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and _ characters, which are keyboard shortcuts for the Wolfram Language named functions Apply, Map, Slot, Function, and Blank.
995
questions
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2
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85
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How to build the following region?
Consider a 3D figure defined by the dependence $\Delta x(z),\Delta y(z)$. One example is a pyramidal frustum, for which $\Delta x, \Delta y$ are linear functions of $z$, and $z$ lies inside the ...
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2
votes
1
answer
51
views
ReplaceAll that works inside Rational?
I'm trying to replace all instances of a 31632259 in a formula with x, but there's something special about how Mathematica ...
- 8,051
2
votes
0
answers
160
views
+500
How to solve the following integrodifferential equation by generic approach?
Consider the following equation:
$$
\frac{\partial f}{\partial t} - p H(t)\frac{\partial f}{\partial p} = \mathcal{I}[p,t], \tag 1
$$
Here, f = f[p,t], with p being ...
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2
votes
2
answers
100
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How to "complete" the table by making all of its rows to have the same number of elements?
Consider the following table:
...
- 4,642
0
votes
1
answer
58
views
Syntax error trying to rewrite expression using rules
I want to use Mathematica to calculate derivatives of some long, complicated expressions. I have an integral with integrand $I_*$ which is a functional that depends on $h(x,t)$ and $\phi(x,t)$. The ...
- 221
0
votes
1
answer
66
views
How to re-organize the table in the following way?
Consider the following table:
tab=RandomReal[{0,1},{5,10}]
How is it possible to convert it into the form of a 2-column table ...
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0
votes
2
answers
100
views
How to combine the tables in the following way?
Consider two tables
tab1 = RandomReal[{0, 1}, {5, 4}]
tab2 = RandomReal[{0, 1}, {10, 4}]
How to quickly make a table where the ith row of ...
- 4,642
2
votes
1
answer
86
views
How to code retarded time in Lienard-Wiechert potential equations?
I have been making strides on my project with the help of others here but have run into another snag: I am having difficulty in expressing the Lienard-Wiechert potentials with retarded time. For ...
- 55
2
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4
answers
132
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1
vote
0
answers
79
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How to emulate the curves and color of the video? [closed]
I found this animation on the internet, it is part of a joke, but I was intrigued by how the video can be emulated with the colors and the curve proposed in the video.The video talks about neural ...
- 309
4
votes
4
answers
156
views
How to check if at least one ordering of the given row matches one of the rows of a table?
Consider some list of elements
...
- 4,642
2
votes
4
answers
215
views
How to check if the given row matches one of the rows of a table?
Consider some table
tabb = RandomInteger[{0, 4}, {5, 4}]
and a row
row = RandomInteger[{0, 4}, 4]
How to check if ...
- 4,642
8
votes
2
answers
349
views
Reverse the rotation of an animated gif and create a mirror image of it
I need Mathematica code to reverse the rotation direction and viewpoint of an animated GIF named "wheel." The current rotation is counterclockwise, and I need it to rotate clockwise while ...
- 309
0
votes
2
answers
108
views
How to automatically convert sub- super-indices to strings?
Consider the following expression:
expr = "\!\(\*SubscriptBox[\(m\), \(t\)]\)"
I would like to convert it to the ordinary string e.g. ...
- 4,642
0
votes
2
answers
91
views
Clip, Select, FirstPosition not working for extracting values from an association based on a range from another list
I have this dataset of associations:
...
- 113
4
votes
6
answers
270
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0
votes
0
answers
27
views
1
vote
0
answers
28
views
Generator of limits of successions according to type of indeterminacy. Correct syntax
I am trying to make a limit generator with 3 columns, number of the exercise, the second column is the limit (perfectly written with n-->00), and the third column is the result of the limit.
I have ...
- 11
0
votes
0
answers
41
views
How do we create a function for the recurrence relation in terms of a dependent variable?
Suppose
S = {{-1.5, 1}, {0, 1}, {1.5, 1}, {1.5, 0.1}, {0, -0.1}, {-1.5, 0}, {1, -1.4}, {-1, -1.5}}
How do we define the recurrence relation as a function of the ...
- 39
0
votes
0
answers
46
views
Way to download all attachments from yahoo.com
For a long time now I want to download the attachments from my yahoo.con mail, only the files, no text, but in batches, so MMA gets into my mail and downloads every attached file it finds in a folder.
...
- 2,253
2
votes
1
answer
104
views
3
votes
5
answers
469
views
How to find the most repeating row?
Consider the following table:
tab={{1,0,0,1},{1,0,0,1},{0,1,0,1},{1,0,0,1},{0,0,0,1},{1,0,0,0},{0,1,0,1}}
Could you please tell me whether there is a command which ...
- 4,642
0
votes
0
answers
51
views
How to compile a code with a table having varying number of columns?
Consider the following table:
...
- 4,642
1
vote
2
answers
98
views
How to extract the following data from the file?
Consider the following file. It has the form
...
- 4,642
0
votes
1
answer
44
views
How to define the following rule for all objects in a compact way?
Consider the following symbolic definitions:
...
- 4,642
4
votes
1
answer
119
views
Put text in Graphics3D syntax?
Some friends from the forum helped me to make this MMA script, I have tried to modify it to put text similar to the image, perhaps with a more beautiful letter, but I can't think of how, I have seen ...
- 309
1
vote
2
answers
126
views
3
votes
2
answers
115
views
How to make two sub-sets each with two distinct elements having a list with 4 elements?
Consider the following list:
list = {{meson1, p1}, {meson2, p2}, {meson3, p3}, {meson4, p4}}
I would like to organize it into two sub-sets, each with two elements, ...
- 4,642
2
votes
3
answers
123
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6
votes
3
answers
861
views
How can I draw this image and if you can make it rotate horizontally and vertically?
I've been looking at the site, but it doesn't occur to me there was a method to obtain the coordinates of the image, but I can't find it. Could you give me a hand?
It's for a poster of the ...
- 309
4
votes
2
answers
193
views
How to tell Mathematica to leave only terms not higher than X power?
Consider the following expression:
expr = a[x]*da[x,t]*db[x,t]c[x] + db[x,z]^2*a[x]^2*d[x] +d[x]^2*da[x,t]db[x,t]+ dc[x,z]^2 + c[x]*dc[x,z]^2*db[x,t]^6
Is there ...
- 4,642
-1
votes
1
answer
190
views
How to simplify the following expression?
Consider the following expression:
expr[s1_, s2_, m_] =
Sqrt[s1 (s1 - 4*m^2)] + c Sqrt[s1^3 (s1 - 4*m^2)] +
d Sqrt[s1^4 s2^2 (s1 - 4*m^2) (s2 - 4*m^2)]
Here, <...
- 4,642
3
votes
1
answer
131
views
How to assign the following rule?
Consider the following object: function[x,a,b]. It is a symbol carrying one "coordinate" x and two indices a,b.
I ...
- 4,642
3
votes
2
answers
381
views
Why the replacement rule works okay for scalars but not okay for matrices?
Consider the following UpSetDelayed:
D[Kstar0[x_, a_], x[b_]] ^:= dKstar0[x, a, b]
It works fine if applied to a scalar ...
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2
votes
1
answer
48
views
How to simplify the following expression of a matrix with complex conjugation?
Consider the following matrix:
...
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0
votes
1
answer
40
views
How to make a rule for the complex conjugation of a symbol?
Consider some symbols piplus, piminus, eta. Let us assume that they appear as conjugated, e....
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1
vote
0
answers
112
views
1
vote
2
answers
85
views
Assigning domain and/or value restrictions to multiple variables at once
Suppose I want to assign value and/or domain restrictions to a set of variables. As an example, let expr be some function of a, b, c, d, and e. Instead of writing, ...
- 3,603
1
vote
2
answers
55
views
3
votes
1
answer
149
views
Why is the code with multiple Do slower than the one without them, and why is For faster than Do?
For some table tab having N rows and n columns, I need to go over all its rows $j$ and ...
- 4,642
0
votes
0
answers
29
views
Omit multiple calculations of the same thing inside a compiled code?
Toy problem
This question arises from the more complicated question involving it as a part.
Assume a 2D table tab. We need to iterate over its rows ...
- 4,642
0
votes
1
answer
273
views
Why are the results of these codes different?
I apologize for the very long question with a relatively complicated code. I am dealing with a real problem, and the question below appeared from my attempt to simplify this problem to ask about it ...
- 4,642
2
votes
2
answers
120
views
Eliminate artifacts in a region region defined by `RegionDifference`
Consider the following region:
...
- 4,642
2
votes
1
answer
179
views
How to get rid of the boundary at the regions merging in the plot?
Consider the following region:
...
- 4,642
5
votes
2
answers
175
views
1
vote
1
answer
47
views
How to make the following region?
Consider the following region shown in green:
It is a part of the annular cylinder with the inner radius $R$ and the outer radius $R+r$, which is cut off from the left and right. Is it possible to ...
- 4,642
0
votes
0
answers
21
views
How to get back from CForm to ScientificForm? [duplicate]
Consider a number
number = 2.*10^20
It is in the representation of ScientificForm.
I convert it to C-form:
...
- 4,642
1
vote
1
answer
45
views
How to adjust PlotRange automatically depending on the value of the function?
Consider the following test function:
func[x_] = x^3 Exp[-x^2];
In general, it may be an arbitrary function without e.g. extrema.
I want to plot it:
...
- 4,642
2
votes
0
answers
63
views
How to find the farthest distance from the point to the region?
Consider the following 2D regions:
...
- 4,642
2
votes
1
answer
38
views