Mathematics
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Jean Marie
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Retired professor (Lyon, France), still with some academic research activities. Having more free time now, I devote it to sharing knowledge, especially in mathematics and its links with computer science.

Some of my answers (a few of them recent) that can be of interest:

Analysis:

PICTURE: Roots of the partial sum of exp(z)

The highest power of 2 less than x

Solving a functional equation using group theory

Infinite product for the cardinal sine

Lemniscates

A recurrent sequence involving Fibonacci sequence

Linear algebra:

Decreasing importance of determinants but...

Eigenvalues of permutation matrices

Relationship quaternions-complex numbers

A special determinant

General Algebra:

Finite fields: polynomial factorization

Non commutative ring of order 125

Geometry:

Equilateral triangle in a triangle

Sierpinski triangle

Trilinear coordinates

Playing with areas in a 5 pointed star

Geodesic triangle in a cone

Equation $SS_1-T^2=0$ of a cone tangent to a quadric

nD Simplex coordinates of vertices

Hyperbolic Geometry

Probability:

Flock of sheep

Markov chain

Geometric probability

2,564
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23
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  • Lyon, France
  • Member for 5 years, 5 months
  • 13,809 profile views
  • Last seen 16 mins ago

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Top posts (2,587)

All Questions Answers
Votes Newest
98 Why does Friedberg say that the role of the determinant is less central than in former times? Nov 4 '16
33 Find all functions $f$ such that $f(x)+f(\frac{1}{1-x})=x$ May 4 '17
25 What are the properties of eigenvalues of permutation matrices? Oct 16 '16
24 Is it possible to have a $3 \times 3$ matrix that is both orthogonal and skew-symmetric? Jan 17 '17
22 Fibonacci sequence and other metallic sequences emerged in the form of fractions Jun 14 '19
21 Find the determinant of $I + A$ Oct 16 '16
21 Three bullets are shot in a sphere. What is the probabilty that all of them end up in the same hemisphere? Jun 6 '16
21 Are there mathematical concepts that exist in dimension $4$, but not in dimension $3$? Sep 4 '19
20 Japanese theorem, in its extended form Jan 20 '18
20 How is this matrix called, and does it have a purpose? Feb 29 '20
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