11 papers
Schwarz and Schwarz as free-boundary minimal disks in a tetragonal disphenoid: exact areas
Steven Finch
Let be the tetragonal disphenoid whose four congruent faces are isosceles triangles with sides , so that the dihedral angles are along one opposite pair…
An exact hypergeometric Weierstrass representation for Smyth's free-boundary minimal disk in the regular tetrahedron
Steven Finch
Smyth (1984) proved that every tetrahedron contains three embedded minimal disks meeting orthogonally, obtained as conjugate surfaces of Plateau…
Elimination of the parameters in an elliptic parametrization of the Schwarz primitive surface
Steven Finch
Let be the curvilinear square bounded by the four circular arcs , , and let . Put \[ θ(ζ)=\arcsin\frac{2(1+i)ζ} {…
The two cubic separable minimal surfaces: and
Steven Finch
A minimal surface in is if it is the zero set of , and if moreover . We announce that there are exac…
Small Matrices with Large Inverses: Unimodular Cases
Steven Finch
How close to singularity can an unimodular matrix be? For ternary cases as increases, exact expressions are unlikely, but upon fixing and assessing -…
Small Matrices with Small Inverses: Unimodular Zerofree Cases
Steven Finch
We consider unimodular matrices such that neither nor contain zero entries. Matrices typically exhibit a trade-off: small imply large . We investigate…
th Roots of th Powers
Steven Finch
Seeking simple, efficient solutions of a matrix equation leads (quite circuitously) to optimizing unimodular zerofree matrices. Canonicalizing such matrices under signed-permutatio…
Popa's "Recurrent Sequences" and Reciprocity
Steven Finch
Dumitru Popa found asymptotic expansions for certain nonlinear recurrences, but left open the numerical evaluation of associated constants. We address this issue. A change of varia…
An Exceptional Convolutional Recurrence
Steven Finch
A quadratic recurrence of Faltung type, arising via ancestral path lengths of random binary trees, turns out to be related to the Painlevé I differential equation.
A Deceptively Simple Quadratic Recurrence
Steven Finch
Standard techniques for treating linear recurrences no longer apply for quadratic recurrences. It is not hard to determine asymptotics for a specific parametrized model over a wide…
Multisum Sets
Steven Finch
Complete infinite multisum sets are eventually linear. After 30 years of sitting in a file cabinet, the proof (thanks to James H. Schmerl) is brought from darkness into light.