How to manipulate expressions structurally, not necessarily complying with the rules of algebra.

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3
votes
1answer
170 views

Derivatives of functions with arbitrary number of variables?

I am trying to define a function f[x1,x2,...,xn] with n integer but not specified. And then I would like this funktion to behave ...
2
votes
1answer
43 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
2
votes
1answer
83 views

What role to sub/superscripts play in Mathematica?

I'm not sure I understand the role of subscripts and superscripts in the Mathematica language. For me, the expression: ...
6
votes
0answers
225 views

Using FunctionExpand to evaluate symbolic derivatives

Some symbolic derivatives of certain special function are not expanded automatically, but FunctionExpand often helps to get a derivative-free closed form ...
4
votes
0answers
237 views

Strange behavior of undocumented RawArray and ArrayObject expressions

I discovered several strange results and inconsistencies while trying to understand what undocumented RawArray and ArrayObject ...
3
votes
0answers
76 views

How to combine DifferenceRoot objects for odd and even-indexed terms

I'm trying to analyze a certain infinite sequence $S$, indexed by positive integers starting from $1$. It can be split into two subsequences: $S^{odd}$ by removing all even-indexed elements and ...
3
votes
0answers
165 views

Why doesn't Log[Gamma[]] simplify to LogGamma[] where it could?

I have been playing with various equations involving amount of permutations in relatively large sets. Easiest way to look at these is something like Log[10, bignumber!] . Often expressions, even ...
2
votes
0answers
46 views

Derivative of vector dot product with respect to a vector

I have the expression: Transpose[gvecI, {2, 1}].x (m[1] + m[2]) gvecI and x are [3x1] ...
2
votes
0answers
81 views

TrigExpand Idiosyncracies

TrigExpand[Sin[x]^2 Log[y]] returns sin^2(x) log(y), as one would expect. However, ...
1
vote
0answers
42 views

Simplifying Expressions for FindMinimum

I am currently trying to apply the FindMinimum function to find the lowest energy of an expression. My current expression as of now is relatively complicated. It is the summation of 48 similar terms, ...
1
vote
0answers
43 views

How to remove parts of an expression

I have an expression where terms Transpose[R].R appear. R is a matrix with the property Transpose[R].R=IdentityMatrix[3]. How ...
1
vote
0answers
40 views

Matching Root[…] objects with patterns, unexpected hidden argument

I needed to write patterns that could distinguish between arbitrary-function and polynomial forms of Root objects, for example, ...
0
votes
0answers
61 views

Loop in a loop, or how to evaluate complex expressions

I need to find $h_{0j}$ for every $1\leq j\leq300$, where \begin{multline*} h_{0j} = \sum_{q=1}^{Q}g_qe^{-\lambda_q j\Delta}\frac{e^{\lambda_q\Delta}-1}{\lambda_q} + \sum_{p=1}^{P}\frac{e^{-\alpha_p ...
0
votes
0answers
27 views

Find out domain after change of variable in integral of d dimensions

Is there a way to tell Mathematica the change of variable you want to do and getting back the corresponding domain? The specific problem I am trying to solve is $\quad \quad\int_{-1}^0 ...
0
votes
0answers
29 views

Extract the divergent/bounded part of a certain expression

Consider I have a power series which is function of $x$. A part of this expression is bounded when $x->\infty$, some remainder is on the other hand divergent when $x$ goes to infinity. What is the ...
-2
votes
0answers
44 views

Find list element matching pattern

I have the following list: {A , B.C , B.C.S[d].S.F} I need to find the index of all elements containing S[d].S, i.e. an ...