This is my home page, where I dump everything that I can think off. Some of the contents are in Spanish, those are listed in the other column.


During September 1996, I had a wonderful 2 week trip to China.


Since I am from Argentina, some people asked me about Evita, after watching the movie (which I have not seen yet). I decided that I might as well place my reply here.

Old Stories about Computers

I've been working with computers for more than 20 years (I wrote that around the year 2000 so, it is close to 35 something now in 2014. Keep counting!). I had a good laugh with a good friend of mine recalling what we did in those days. I've put together some of this old stories about old computers.

Babbage's Difference Engine

Talking about old computers, here is the grandmother of them all, Charles Babbage's Difference Engine, which actually was an automatic calculator and just one step below his Analytical Engine a true computer as we now understand them; neither one ever built.

Yahoo User Interface Library (YUI)

I've been contributing to this open-source project for quite a while and I wrote some examples showing how to use the library and some articles about it and, most recently, I wrote a book about it: YUI 2.8: Learning the Library.

PHT - PHP with embedded HTML

In the days when PHP was probably the most popular server-side scripting language for web sites, I had this idea that producing HTML from PHP should be much easier than it was. Pretty much like JSX does today integrating HTML within JavaScript. I managed to modify a PHP compiler to accept my version of PHT (PHp with embedded HTml) and produce regular PHP. Here is the documentation for it, just for historical reasons, stripped off the links to the now obsolete stuff (PHP version 5 was current then).

Spanish for English Speakers

Spanish is a phonetic language with very few exceptions. Here are the most basic rules.


My e-mail is: satyam@satyam.com.ar

Penrose Tiling - Mosaicos de Penrose


Esta es mi página de WEB, donde vuelco todo lo que se me ocurre. Parte de su contenido está en inglés y está listado en la otra columna.


Notas, comentarios, fotos y artículos.

Máquina de Diferencias de Babbage

La Máquina de Diferencias de Charles Babbage es quizás la antecesora de las computadoras actuales.  En realidad, una calculadora automática, está apenas un escalón por debajo de la Máquina Analítica, que podríamos considerar una computadora real. Babbage nunca terminó de construír ninguna de ellas.

Nuevo Retiro

Ideas tomadas del transporte público de Madrid y Barcelona que podrían ser aplicadas en Buenos Aires.


Mi correo es :satyam@satyam.com.ar

The design above is based on Roger Penrose tiling pattern. This simple design was thought to be impossible to exist, and thus was not even explored by mathematicians who, amongst their very strange interests, lies the filling of surfaces with repeating patterns, that is, tiling.

It is obvious how to fill a surface with triangular, square or hexagonal tiles, and several others derived from them and their combination. The tiling pattern on a five axis symmetry was thought impossible to do with a limited number of tiles. Penrose showed that, indeed, it is possible with just two diamond shaped tile patterns (there are other shapes derived from these). It is still thought to be impossible to do with pentagonal tiles, unless you use an inordinate number of extra shapes to fill in the holes. Note, after all, that though the symmetry is five sided, the tiles themselves are four sided.

This particular figure is composed of yellow and green tiles which are actually of the same shape and blue ones which are the second shape. The red border is just to frame it. There are some green tiles cut in half on the border, and this was made just to make the frame fit, but this design can actually go forever with just the two basic tiles.

La figura de más arriba está basada en los mosaicos de Roger Penrose. Se había creído que este diseño no podría existir y nunca había sido explorado por los matemáticos que, entre sus muy variados y extraños intereses está el llenado de superficies con figuras repetidas, esto es, hacer mosaicos.

Es obvio cómo llenar una superficie con tejas triangulares, cuadradas o hexagonales, y varios otros derivados de ellos y sus combinaciones. No se pensó que existiera un mosaico con cinco ejes de simetría, que pudiera hacerse con un número finito de tejas. Penrose mostró que, efectivamente, es posible hacerlo con sólo dos figuras en forma de rombo. (existen otras figuras derivadas de estas mismas). Aún se cree imposible el uso de mosaicos pentagonales a menos que se los complemente con una buena cantidad de otras figuras para completar los huecos. Nótese que, a pesar que la simetría de la figura completa es de 5 ejes, los mosaicos en si son cuadriláteros.

Esta figura en particular está compuesta de tejas amarillas y verdes, que son exactamente iguales, y tejas azules que son el segundo tipo de mosaico. El borde rojo es simplemente un marco. Sobre el borde, hay algunas tejas verdes cortadas a la mitad para que el marco cerrara mejor, pero este diseño, en realidad, puede seguir eternamente con los dos tipos de tejas solamente.