26,892 reputation
356102
bio website ilorentz.org/beenakker
location Leiden, The Netherlands
age
visits member for 4 years, 9 months
seen 1 hour ago
physicist at Leiden University

10h
revised Advanced Differential Geometry Textbook
added 77 characters in body
11h
revised Advanced Differential Geometry Textbook
added 420 characters in body
11h
answered Advanced Differential Geometry Textbook
19h
comment Approximating a divergent integral with modified Bessel functions of the first and second kinds
the value of $I$ is $\infty$, what is there to evaluate or approximate?
2d
revised Quantum Hamiltonian for an Inverse Cube Force Law
deleted 61 characters in body
2d
answered Quantum Hamiltonian for an Inverse Cube Force Law
2d
comment Differentiability of the function $\frac{x}{1+\|x\|}$
yes, just calculate the derivative.
Aug
27
answered Errata database?
Aug
26
answered Orthogonal polynomials with respect to the lognormal distribution
Aug
26
comment Singular integral equation
there is no unique solution, a simple choice is $u(t)=u_0+(u_1-u_0)t+at(t-1)$, and then adjust the free parameter $a$ so that the integral over $K(t)u(t)$ equals $M$.
Aug
26
revised Fair surfaces - general mathematical theory
added 223 characters in body
Aug
26
answered Fair surfaces - general mathematical theory
Aug
22
comment Euler's totient function relative function
I don't think it has a name, but its reciprocal is closely related to the abundancy index (it has the same density), see ams.org/journals/proc/2007-135-09/S0002-9939-07-08771-0/…
Aug
20
comment ROC curve analysis
en.wikipedia.org/wiki/Receiver_operating_characteristic
Aug
19
revised Pi and the primes: a pattern related to the Ulam spiral
ImageShack to imgur
Aug
19
revised Rooks on a lifeline
ImageShack to imgur
Aug
19
revised Nearest trio of neighbours for non-intersecting ellipses
ImageShack to imgur
Aug
19
revised Listing ORCiD in LaTeX papers
added 290 characters in body
Aug
19
answered Listing ORCiD in LaTeX papers
Aug
19
awarded  Populist