Jacob Siehler
Mathematics Department
Washington & Lee University
Email: siehlerj@wlu.edu
Office: Robinson Room 4
Home SpaceCurve Spivak Mathematica Perl

SpaceCurve

A free OS X application for exploring parametric curves.
(Download, Documentation)

Features Screenshots (click for full-size version):
SpaceCurve Differential Geoemetry Screenshot 1 SpaceCurve Differential Geoemetry Screenshot 2 SpaceCurve Differential Geoemetry Screenshot 3


Spivak

A free OS X application for exploring parametrized surfaces.
(Download Regular version, G5-Optimized version; Documentation)

Features Screenshots (click for full-size version):

Spivak Differential Geometry Screenshot 1 Spivak Differential Geometry Screenshot 2 Spivak Differential Geometry Screenshot 3 Spivak Differential Geometry Screenshot 4
Tangent plane to a torus Geodesic on a stretched wireframe torus Geodesic segment and principal curvatures on a pseudosphere Tangent plane on an annular section of a saddle surface

Mathematica notebooks

2xN-adjacency-free.nb, PDF
Enumerating selections from a 2xN grid with no horizontal or vertical adjacency.
cpanimate.nb
A notebook for demonstrating how the critical point structure of a 1-parameter family of functions changes as you vary the parameter. You get an animation showing the graph of the function beside its contour map; the zero sets of the partials are color-coded, and critical points are identified, classified by the 2nd derivative test, and displayed both on the contour map and the graph of the function. Watch critical points appear, split, merge, and disappear as the parameter changes. I really like this one.
levelsets.nb
Level sets of a function of a function of two variables shown on the graph of the function and in a contour map simultaneously; step through the animation and watch the topology of the level sets change as you pass through critical heights.
osculating3d.nb
Moving frame and osculating circle animations for space curves.
osculating2d.nb
Moving frame and osculating circle animations for plane curves.

Perl

registrar.plDownloads my class rolls from the registrar's site into Excel-readable files.
sneeze.plGenerates this important table of data.
arxiv-keywords.plGenerates selective RSS feeds from the arXiv What's New page