Questions tagged [expression-construction]
The expression-construction tag has no usage guidance.
108
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How to exclude singularities for `NMinimize`
I have an messy expression and want to apply NMinimize to it, have no idea how to force NMinimize to ignore the singularities it ...
- 336
0
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1
answer
78
views
How to modify the order of symbols to make the result look more well and use some fixed expression 1-q, 1-c-q and so on?
In most cases, my expressions are quite complex, like the following expr and expr2. How can I make them look better, for instance, I want to use expressions like 1-q or 1-c-q and so on.
- 169
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43
views
Conversion of an expression to function yields Tag Plus in ... is Protected error
I'm trying to implement polynomial interpolation. My current implementation involves generating an expression that is the final equation that will be plotted. While plotting the function itself works ...
- 33
3
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2
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167
views
Precise control of fraction expression
It seems that expression for fraction differs
when the number of terms in the numerator is more than 2.
...
- 4,315
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2
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132
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Elegant way to validate expression?
Suppose I'm using the expression Person[fn_String, ln_String] as a data expression, and want to prohibit the creation of expressions where ...
1
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1
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130
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Fitting an inverse power law [closed]
Is there any reasonably fast way of finding a function of the type
that best fits a given data, for some K and n? For example, the following data closely follows an inverse power law
...
- 4,903
0
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1
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55
views
Generating a 2 variables polynomial with constraints
I would like to generate automatically a polynomial in two variables $(s,t)$ which is symmetric under the exchange of those variables. There are three kinds of terms; at order $k$, we have
$$(s+t)^k, \...
-1
votes
1
answer
51
views
Swap Composite Command Components
Let's take a composite Mathematica command:
A[B[]]
where A and B - two arbitrary ...
- 2,444
1
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1
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74
views
1
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1
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172
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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 ...
- 2,467
1
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1
answer
120
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:
...
- 9,677
2
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0
answers
116
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
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63
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
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251
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4
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127
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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:
...
- 343
1
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2
answers
67
views
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 ...
- 1,698
2
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0
answers
34
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 ...
- 332
3
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2
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755
views
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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319
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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{...
- 51
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2
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194
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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 ...
- 1,897
2
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1
answer
43
views
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
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1
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51
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
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0
answers
183
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 ...
- 7,273
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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.
...
- 9,523
0
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1
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178
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:
...
- 67
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50
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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 ...
- 1,613
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107
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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}
]
...
- 2,060
8
votes
2
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265
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
...
- 2,520
1
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3
answers
86
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
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1
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87
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 ...
- 1,698