Unanswered Questions
456 questions with no upvoted or accepted answers
18
votes
0
answers
312
views
Reduce[Sin[x]==0,x] splitting odd and even multiples of Pi
as from Title, I'm wondering why Mathematica does not automatically give a single, simple solution for the problem
Reduce[Sin[x] == 0, x]
for which I obtain the ...
- 275k
12
votes
0
answers
412
views
Simplify and Sqrt, inconsistent behavior?
I have encountered some problems when using Simplify with expressions containing a square root and isolated a following test case
...
- 47.2k
11
votes
0
answers
185
views
Eliminate variable with partially documented Solve feature Solve[eqns,vars,elims]. Robust?
The Eliminating Variables section on Manipulating Equations and Inequalities documentation quotes an otherwise undocumented feature for Solve
...
- 37.7k
11
votes
0
answers
9k
views
How to simplify an expression, using a known term substitution?
I have a complicated algebraic expression that involves a lot of similar terms. In particular, I have a complicated sub-expression involving sums and products that I would like to denote $\alpha$. I ...
- 11.7k
11
votes
0
answers
653
views
Faster simplification of linear combinations of some specific functions
After some profiling I've found that my program spends most of its time in the simplification step. The program uses my simplification function many times (over different data). My calculation is not ...
- 456
8
votes
2
answers
1k
views
Spherical harmonics and Laplace operator
The spherical harmonic function $Y_l^m(\theta,\phi)$ is defined to be an eigenfunction of the angular part of the Laplace operator with eigenvalue $-l(l+1)$. In other words, it solves the PDE:
$$\...
CommunityBot
- 1
8
votes
0
answers
646
views
What is a "generic case"?
Introduction
With this question, I am coming back to a long-standing issue I have with Mathematica's concept of a "generically correct" result. The basic idea seems to be, vaguely, that if a ...
8
votes
0
answers
2k
views
Is it possible to simplify an expression in vector form, which involves crossproduct and dot product?
I often need to simplify expressions involving cross product and dot product, for example:
f = Dot[Cross[Cross[p1 - p, e1], Cross[p2 - p, e2]], Cross[p3 - p, e3]]
...
- 71.6k
7
votes
0
answers
154
views
Need explanation on strange behavior of Simplify under given assumption
This is quite surprising to me.
Simplify[a == b, {a == {1}, b == {1}}]
a == b
does not evaluate the equality, while
...
- 72.3k
7
votes
0
answers
95
views
Unexpected behaviour of Simplify
I'm evaluating an expression and to me the result should be True but Mathematica is giving me a different result.
...
- 233
6
votes
0
answers
234
views
Simplification depends on the names of variables
I am sure this issue has been discussed here, but it has never been asked whether this behavior is a bug.
Therefore my direct question to the community: do you think this behavior is a bug?
...
- 23.2k
6
votes
0
answers
475
views
How to get mathematica to simplify a result
I have the following output $\text{Li}_2\left(3-2 \sqrt{2}\right)-4 \text{Li}_2\left(-1+\sqrt{2}\right)$.
This turns out to be equivalent to $\displaystyle\log^2(1+\sqrt{2})-\frac{\pi^2}{4}$.
How ...
6
votes
0
answers
298
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 ...
5
votes
0
answers
143
views
Why the ComplexExpand is not working here?
The ComplexExpand seems not to be working in the following where all variable are real:
...
- 867
5
votes
0
answers
589
views
Manipulating tensorial terms with xAct, ToCanonical is not perfoming well
I am trying to calculate perturbations of some complicated Lagrangians. Using xAct and more specifically VarD to perform the perturbations the expressions become ...
- 51