What's New

2009-06

GeoGebra used on this site has been updated to the latest version, 3.2. For a feature list of GeoGebra 3.2, see: Release Notes GeoGebra 3.2.

2008-12

Spent about 6 hours converting HTML 4 Transitional to HTML 4 Strict for my Visual Dictionary of Special Plane Curves website. There are 410 html pages. Note that all html pages are valid html (i.e. passes W3C's HTML validator), both before and after. Even with valid HTML, the trasition is not trivial. The trasition are done semi-manually with emacs. (in particular, using its feature of Interactively Find and Replace String Patterns on Multiple Files)

Besides convertion to html 4 strict, i also took time to clean up the pages. In particular, change various html formatting to be some consistent canonical form. And, change the html tag use so that their semantics can be mechanically parsed. This is to pave the way for semantic web, and perhaps in 2009, i'll transform the site again to xhtml. The goal is that, the site can be easily transformed to any other format such as PDF or others for book publishing, by mechanical means, and without losing any info or manually diddling with display formatting again.

Almost all the changes are changes of appearances or formatting. There is not much content or math additions.

Changes

Here's some description of the changes for those technically curious:

Changes For Html 4 Strict or XHTML

In html4strict, “<br>” must be inside block level tags.
Image tag “<img ...>” needs to be enclosed in a block level tag such as “<div>” in html4strict.
Lowercase all tag names. e.g. “<P>” should be “<p>”. This is esp important when converting to xhtml since xml is case sensitive.
Add closing tags to “<p>” and “<li>”. Not required by html4strict but needed for xhtml.

Semantic Formatting Changes

Change use of “table” for side-by-side images to a more semantically correct form.
Often i need to display 2 illustrations side by side. I have used “<table>” for this. But now some of them are formated with “<div class="img">” for better semantic interpretation. I haven't found a optimal solution yet.
A canonical format for Yate's Verbatim quote in the history section of each curve.
Used a special link tag for linking to special files (Mathematica notebook, geometer's sketchpad, cabri geometry, graphing calc, etc files).
Remove the “;” separator when there is a sequence of links to special files (gsp, mma, fig, etc).
Change all “(* XahNote: ...*)” to a canonical form. Something like: “<span class="xahnote">...</span>”. These are notes to myself, some makes good exercise problem.

Misc changes

Replace all “sinusoid” to “sine curve”. (use modern terms. Similar is “osculating circle” to “tangent circle”)
Convert all Mathematica files compressed with gzip format to zip.
Old items in this “What's New” page is now moved into separate pages.

To Do

Convert all Geometer's Sketchpad files (“.gsp”) to GeoGebra.
Convert all Cabri Geometry files (“.fig”) to GeoGebra.
Add “Robert Yates” excerpt to every curve's history section.
Add E H Lockwood's excerpt to every curve's history section.
Wikipedia linkify mathematician names, esp the history section.
Remove the “<hr>” in “"<hr>\n<h3>"”. Find a canonical way to solve this css problem. (because the hr stops css float. For some header, i need float stopped, but not others.)
Use canonical format for author names that uses abbrev. e.g. replace “J.D.Lawrence” to “J D Lawrence”. (in general, period is semantically used only for end of sentence.)
Check all “<br>” for possible deletion. Regex search for “"<br> *\n*\(<p|<table\|<ul|<ol)"”
Add caption to illustrations. e.g. search for “following illustration ...”, move the text as img caption.
Remove the dot in “PDF version of this page.</a>” and “<p><a class="mma" href="deltoid.nb.zip">Mathematica Notebook for This Page</a>.</p>”
Do something about “<p><B>Parametric</B>...”. Devise a canonical format for listing formulas of curves, e.g. parametric, polar, algebraic equation.

2008-04

Added:

Archimedean spiral

Inversion of Archimedes's spiral

Real Rose Curve

Peaucellier Linkage on a line

Thales's Theorem

Converse of Thales's Theorem

Archimedes Circle

Inversion of A Line

Inversion of A Circle

Inversion of Sine Curve

Uploaded about 170 scanned pages of the book by Yates, here: “Curves And Their Properties” by Robert Yates. Please support this website by making a donation or buy a downloadable version.

The site is now heavily linked to Wikipedia. Mathematician's names in the history section are linked to Wikipedia, and any other theorem or relevant fact appeared in this site's text but not explained, are linked to Wikipedia. Also, every curve page now has a link to Wikipedia's entry at the bottom.

Dead links or links to college student's works are removed.

2008-03

Spent a couple hours and updated the Printed References On Plane Curves page. With links to Wikipedia and amazon.

Figure 8 Curve

Adde material to Cornu Spirals.

Cornu Spirals.

Still in the process of phasing out Geometer's Sketchpad files on the site. There are like 120 of them. Eventually, they should all be in one single zip file for download. Geometer's Sketchpad is replaced by GeoGebra.

Tractrix Tracing

Sine Curve

Updated the page: Naming and Classification of Curves.