Questions tagged [expression-construction]
The expression-construction tag has no usage guidance.
100
questions
1
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views
Need to find a unique mathematical expression (not in documentation) that is as short as possible but takes a good amount of time to evaluate
I am writing a public ResourceFunction and I need a good clever use case that should not appear to emulate any examples in the official documentation but will ...
- 1,787
1
vote
1
answer
105
views
How to convert this Mathematica expression to another, as described here?
I am working on a function of which the core will consist of something like:
...
- 9,337
0
votes
0
answers
56
views
Get depth of vertices in TreeGraph
I want to get the depth of each vertex in a TreeGraph, g. I might convert g into an ...
- 2,648
2
votes
0
answers
55
views
Store pattern names in variables, and use them in Condition (/;)
I am trying to create patterns whose form is not hard-coded, and which are not explicitly directly written. For that I want to use one list of pattern names to name some parts of a ...
- 483
0
votes
2
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30
views
How to turn FindFit result into function within a Module context
I'm trying to construct a 'normal' function (with formal parameter) from the FindFit result within a Module context.
While this works on a global level:
In :=
...
4
votes
1
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246
views
4
votes
1
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120
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Alternatives in pure function construction
When I declare a function f in the following form:
f[a|b] := 1
then I can use it like:
...
- 333
1
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2
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55
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Replacements: using condition to restrict to parts that satisfy a Boolean expression
I need to replace all integers k in a list with {k} and tried:
EDITED: as a clarification: I mean all integer elements of a list, not all integers in the list, so in the following example, only 4 ...
- 1,004
2
votes
0
answers
32
views
Setting pieces of "matrices" - unwanted behavior
I am constructing matrices whose elements are lists themselves (of varying length), and am (re)setting the entries of these matrices using among others the "All" command. It seems that in ...
- 180
3
votes
2
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351
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Creating of the Jordan Canonical Form
I have a matrix polynomial P(s) and the Jordan blocks of P(s) corresponding to every eigenvalue sj (j=1,...,k).
How can the Jordan Canonical Form be generated, i.e. the block diagonal matrix which has ...
- 31
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4
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157
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Creating a block diagonal matrix when the submatrices in the diagonal are unknown
Let us assume that we have an integer $j$ $(j=1,2,...,k)$ and that for every $j$ is generated a matrix $P$ of dimensions $j$x$j$ . For example, if $j=1$ then $P=(-2)$.
If $j=2$ then
$$R = \begin{...
- 41
1
vote
2
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109
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How to sort out/ extract positive and negative powers as list?
I have the following expression
expr = x1^d1 * x2^d2 * x3^d3;
where d1,d2,d3 can contain negative values/expression i.e. in ...
- 973
2
votes
1
answer
39
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Formula: setting parameters vs replacement, different results?
I have a question that may sound stupid and have an easy answer - but I currently do not see it.
I have defined a function of four variables, $f[a,b,c,d]=...$, in what I think is correct Mathematica ...
- 43
0
votes
1
answer
47
views
Nest expressions of several arguments
I have the following function:
Q[r_, f_, s0_] := Q[r, f, s0] = F[r, s0] D[f[s0], s0]
By calling
Q[r, Q[r, f, s0], s0]
I ...
- 153
3
votes
0
answers
138
views
Computations with OptimizedExpressions without completely expanding them
I have to manipulate huge expressions that are rational functions of many (∼30) variables with integer coefficients. Storing them just as a ratio of two polynomials would be impractical. But they can ...
- 6,846
2
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0
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60
views
How to do an arbitrary expression growth in Mathematica?
I want to write a function that can be used to grow an expression from a seed or another existing expression based on part specification.
...
- 8,105
0
votes
1
answer
116
views
Help with printing table data
I am looking for the way of building a Table in a fast way. My true table evaluates huge functions with a system of differential equations . Let us for simplicity consider this:
...
- 47
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46
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How to generate nested expression?
I've found some related questions, but nothing has really helped me to do what I want to do.
Given a list of variables L and a parameter ...
- 1,303
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0
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97
views
Is there a good reason why `Slot[]` is not an atomic expression?
Here's a good reason why I think it should be,
Map[ If[AtomQ@#, #->"is an atom", #->"not an atom"]&
, {"hello",Range@3, # &}
, {-1}
]
...
- 1,970
8
votes
2
answers
210
views
Using `With[...]` with a list specification as a variable [duplicate]
If you have some defined function, say f[a_, b_ c_, x], one can initialize this by using With[...] as
...
- 2,291
1
vote
3
answers
84
views
Summation and product term expressed in Mathematica [duplicate]
I have the following term which I would like to express correctly in Mathematica:
$$\sum_{i=1}^{m}\frac{1}{\prod_{j=1,j\neq i}^m(\rho_i-\rho_j)}$$
This means that for $m=3$ for example you should ...
- 181
0
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1
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60
views
Displaying positions in expression tree
Can one display the position of each character in an expression tree? For instance: g[h[i, h], l] should be displayed using TreeForm where each character is ...
- 1,004
0
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1
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82
views
How to pass an expression as list elements for a Mathematica command
I'm trying to build a generic function that will calculate sums on different iterators.
To simplify let consider:
...
- 3
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0
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64
views
Transform String to Expression [duplicate]
I have a variable postVector and another called CHKpostVector. Both are global variables.
Only the variable ...
- 159
2
votes
3
answers
2k
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How to define constants in Mathematica like c1,c2,c3,...cn?
Manually defining the constants is tedious if the 'n' is large. how to do this?
- 1,649
3
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1
answer
82
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Generate multivariate monomials with constraints
I'm trying to generate multivariate monomials in variables $p_1, \ldots, p_n$. Each monomial has either $p_i$ as a factor, otherwise $(1-p_i)$. I need to generate all monomials which have exactly $k$ ...
- 131
3
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1
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89
views
Creat a matrix with boundary condition
I would creat a symmetric matrix, but how can I set the boundary in Subscript?
...
- 1,624
7
votes
2
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209
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Constructing expressions using Sum vs Array[... Plus] vs Plus@@Table[...]
For constructing a sum of terms which are symbolic, I noticed that in addition to
...
- 19k
-5
votes
1
answer
77
views
Translation of GLSL expression (2) [closed]
What's the most compact WL translation of this GLSL expression:
length(max(vec2(x,y),s))
?
- 588
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votes
0
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87
views
Generate a system of linear differential equations from a coefficient matrix
I want to generate a system of linear equations that is stable. For that I generated random coefficients and divided the 10 by 10 matrix by the largest eigenvalue and set the diagonal to -1:
...
- 2,703
21
votes
4
answers
1k
views
Is expression in Mathematica well defined?
According to Mathematica, everything is an expression. So an atom is also an expression. But in other parts of documentation, they say that an expression is of form ...
- 1,029
1
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0
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91
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How to send Map[Plus[1, #] &, {1, 2, 3}] to Mathematica from C# via IKernelLink?
Here is a piece of my code
...
- 11
4
votes
4
answers
1k
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Replace element of a matrix with condition
consider a matrix
$\left( \begin{array}{ccccc} 0 & 0 & 1 \\ 1 & 0 & 0 \\ 1 & 1 & 0
\\ \end{array}\right)$
How do I do a program that does these steps
1-Replace each ...
user44376
4
votes
4
answers
380
views
Generating a family of 0-1 matrices satisfying a particular property
I'm looking for an elegant way to generate the set of all possible matrices that satisfy the following properties:
Each matrix has 9 rows and c columns, where 1<=c<=9.
Each matrix has exactly ...
- 183
10
votes
3
answers
169
views
Graph that shows how symbols are used in an expression
I would like to make a graph to show how symbols build up an expression. For example, the matrix multiplication
$$
\left(
\begin{array}{ccc}
a & b & c \\
d & e & f \\
\end{array}
\...
- 1,479
-1
votes
1
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50
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Producing the same output as Tuples[{0, 1}, 4]? [closed]
How can I use the functions decimalToBinary and padWithZeros to produce the same output as ...
- 1
4
votes
3
answers
308
views
Handling multi-part equations
How are multi-part equations best handled? For example, take the torsion equation:
We could express part of this equation like this:
...
- 3,896
1
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2
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89
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How to generate expression a + a1 e1 + a2 e2 + a12 e12 (subscripted)?
Sorry to ask this twice. I thought I could get away with just a0 + a1 e1 + a2 e2 + a3 e1 e2, but for my application I can't. I can generate a + a{1} e1 + a{2} e2 + a{12} e12 (subscripted), but that's ...
- 411
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3
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190
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How to make RawBoxes to be Expression
expr = First@
Level[Values@
WolframLanguageData["Plot",
EntityProperty["WolframLanguageSymbol",
"DocumentationExampleInputs"]], {3}]
Plot[Sin[...
- 23.4k
1
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4
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316
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How can a generate an expression like a0 + a1 e1 + a2 e2 +a3 e3 + a4 e1 e2 + a5 e1 e3 + a6 e2 e3?
I wish to input n and then generate an expression. It would look like the above when $n = 3$. I would like to use subscripts for ...
- 411
4
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3
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310
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a function to extract all subexpressions from an expression
Can somebody help me with a function f such that it extract all sub expressions (i.e. looking down the expression tree) from any expression given to it and also a ...
- 8,105
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votes
1
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78
views
1
vote
0
answers
79
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How Defer[1+Evaluate[1+1] work?
I want to generate some expressions.
The expression is not evaluated expect some parts will evaluate first.
A simple example is
Defer[1+1+1] and in this expression ...
- 711
0
votes
1
answer
58
views
2
votes
1
answer
306
views
How to overload the operator "*" as KroneckerProduct [closed]
Can I use the expression below
a * b * c * d
for short to instead
KroneckerProduct[a,b,c,d]
automatically when a,b,c,d are ...
- 711
0
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1
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88
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Solving equations with change of variables is not working?
I want to express it in the form
$$\text{expr=}\int_{-\infty}^{\infty}C_1\exp\left(-t^2\right)f(t)dt$$, i.e., the integrand is a bounded smooth function $f(t)$ times $\exp(-t^2)$ and the domain of ...
6
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3
answers
528
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How to convert a string into a structured list
I am trying to use an efficient notation for the timing of sounds that i can play in Mathematica.
I would like to parse the string
"{ab{c{de}}f}"
as the list ...
- 103
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votes
1
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60
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Is it the correct syntax with TransformedDistribution?
I define a function as f[x_] := ...;which is in fact the PDF of a random variable $X$. The PDF if given by $f_X(x)$.
Let $Y$ is a random variable, which is the ...
1
vote
2
answers
503
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How to find the lowest power in multi-variable expression?
I am sorry for asking a similar question again. I asked How to find the lowest power of variable in expression? and I got a wonderful answer, but I have one more question for a multi-variable ...
- 1,726
3
votes
2
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1k
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How to find the lowest power of variable in expression?
If I have expression like
a1/x +a2/x^2 + a3/x^3
I want to return 1/x^3. In general case,
...
- 1,726