Jakub's blog

Intelligent design

2005-09-27T20:15:00.000-07:00

There is an interesting article in the Guardian about a legal battle concerning the teaching of evolution here.
On my website, there are some new pictures from our recent trips
to Caesaria and Jerusalem.

Two articles about evolution

2005-08-18T11:19:00.000-07:00

There is an interesting column
in the Guardian about Darwinism.

A paper explaining for example the problems with the "intelligent design"
"theory" (used loosely) is available in The New Republic.

A paper on history of cryptography

2005-08-18T03:58:00.000-07:00

An informative paper about history of cryptography
can be found here.

It's been a while ...

2005-08-03T01:04:00.000-07:00

...since I last posted up anything. Well, it was. Anyway, I hope to update my blog more regularly now. A couple of interesting links:

There is an enthusiastic article about Pynchon's Gravity's Rainbow in the bookforum.

A highly readable paper about Hume's argument concerning testimony applied to parapsychology can be found here. Not that I care too much about parapsychology, but it is always interesting to see rigorous arguments applied on the boundary of science (or past
the boundary?). I hope this does not sound too Kuhnian...

Classic papers in computer science

2005-04-05T05:08:00.000-07:00

Prof. Christos Papadimitriou gave this year's Perekis lecture at Weizmann, mainly about the game theory and simulating the internet. During the talk he mentioned that last year he gave a course in Berkeley, called Reading the Classics (referring to Classics in CS). One of the benefits is that there exists a webpage with links to those classic papers - see his webpage (it contains for example the Turing paper or the Shannon paper on information theory and many others).

Expressions in MatLab

2005-04-04T14:02:00.000-07:00

Maybe somebody will find this useful... I had the following problem. Given a hyperbolic curve

f(x)=(x^s cos(x), x^s sin(x))

for x in [0,1], find the length. The only software available on my computer was MatLab. I was more familiar with other programs before. The main problem turned out to be how to switch from one representation of expressions to the other. The trick is to use the function char to
produce a string representation of the expression, and then apply functions inline (resp.
sym) to produce the inline (resp. symbolic) representation.

Let us choose s=2.5. The solution I came up with (after searching the web for a while) was the following. There are two types of expressions in MatLab: inline and symbolic. Thus the commands (the commands in MatLab in this post will be typeset in courier):

syms x;
f=[x^2.5*cos(x) x^2.5*sin(x)];

produce a symbolic expression f. One can differentiate it by

df=simplify(diff(f,x));

take the norm by

ndf=sqrt(df(1)^2+df(2)^2);

and then try to integrate by say

int(ndf,x)

The main problem is that the program cannot find a reasonable symbolic expression for the integral (it involves some elliptic functions). The command quad only takes an inline expression. Thus

ndfin=vectorize(inline(char(ndf)));

produces the symbolic expression dfin for the derivative
(the vectorize command is important for quad - the numeric integration procedure - to work properly). Now

quad(ndfin,0,1)

produces the desired length.

I'm almost sure this is not the optimal way of doing this, but it works...

Last, but not least - if one has an inline expression g, then

gsym=sym(char(g));

produces a symbolic expression gsym, which can be dealt with appropriately.

A couple of interesting art links

2005-02-17T05:31:00.000-08:00

There is an interesting article in the Guardian
about the forthcoming exhibition of Caravaggio's paintings
in the National Gallery.

There is an installation due to Christo and Jeanne-Claude in
the Central Park, which is quite spectacular.

A bit of history

2005-02-16T22:41:00.000-08:00

I was really surprised to find a website
of the village where my great-grandmother
grew up - Teleci.

On the other hand, my maternal grandmother lived in Svitavy, and my
paternal grandmother lived in Vsetin,
that is in Valachien. My favourite quote from the movie
"Vsichni dobri rodaci" is: "Comrades, we all know
that the Valachs came here by jumping from one tree
to another.", which even my father laughs at (though
he grew up in Vsetin). ...talking about my father,
several of his photographs are shown in
this gallery.

Links to friends' pages

2005-01-07T20:13:00.000-08:00

Here are several links to my friends' pages (in alphabetic order):

Culvera's diary

Had

Honza Rychtar

Honzyk

Jirka Spurny

Vigo

There might be more in the future.

Links to my schools

2005-01-05T23:49:00.000-08:00

Here are several links to educational institutions I attended.

Gymnazium Voderadska

Whitgift School

Faculty of Mathematics and Physics, Charles University

Vrije Universiteit

University of Missouri at Columbia

And here is a link to my current employer:

Weizmann Institute of Science

Sorry, this is more or less mainly for my use. If you apply for an American visa
nowadays, they ask you for phone #'s of your highschools (at least last time they did),
so it's good to have this information accessible.

First post

2005-01-05T13:41:00.000-08:00

Hello, this is the first post. Hopefully, there'll
be more in the future. My homepage is

http://www.wisdom.weizmann.ac.il/~duda

There is also my email.
Jakub

View Blog