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Questions tagged [expression-construction]

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1 vote
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 ...
ExpressionCoder's user avatar
2 votes
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 ...
Stijn's user avatar
  • 332
3 votes
2 answers
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 ...
xelen's user avatar
  • 31
1 vote
4 answers
319 views

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{...
arod's user avatar
  • 51
1 vote
2 answers
194 views

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 ...
BabaYaga's user avatar
  • 1,897
2 votes
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 ...
Al Waurora's user avatar
0 votes
1 answer
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 ...
Svetlana's user avatar
  • 153
3 votes
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 ...
Vladimir Reshetnikov's user avatar
2 votes
0 answers
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. ...
user13892's user avatar
  • 9,523
0 votes
1 answer
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: ...
aluuzz's user avatar
  • 67
0 votes
0 answers
50 views

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 ...
TumbiSapichu's user avatar
  • 1,613
1 vote
0 answers
107 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} ] ...
Fortsaint's user avatar
  • 2,060
8 votes
2 answers
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 ...
user27119's user avatar
  • 2,520
1 vote
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 ...
Y.L's user avatar
  • 181
0 votes
1 answer
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 ...
ExpressionCoder's user avatar

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