What caught my attention is the fact that this implementation is about a hundred times slower than a C implementation, mostly because Tcl (without any extensions), lacks an efficient way of handling arrays.

On my machine, a C program finds out all the primes below two million and computes their sum in about 0.3 seconds. The Tcl program does the same thing in about 40 seconds.

The main reason behind this performance issue regarding lists in tcl is the fact that the lreplace command doesn’t actually replace. It returns a new list, and does not modify the existing one. The solution is using the so-called “K-combinator” to make the lreplace work in-place. I need to further investigate this, and maybe use some other languages like perl or python for benchmarking purposes against tcl. Anyway, below is my pure-tcl implementation of the “sieve of eratosthenes”.

 1 #!/usr/bin/tclsh
 2 
 3 #Find all primes up to a given number
 4 
 5 proc K {x y} {set x}
 6 
 7 set n [lindex $argv 0]
 8 set garbage [list]
 9 set flags [list]
10 
11 for {set i 0} {$i <= [expr {$n-1}]} {incr i} {
12     lappend flags 1
13 }
14 
15 set flags [lreplace [K $flags [set flags {}]] 0 0 0]
16 
17 set p 2
18 
19 while {[expr {$p*$p}] < $n } {
20     set j [expr {int(pow($p,2))-1}]
21 
22     while {$j < $n} {
23         set flags [lreplace [K $flags [set flags {}]] $j $j 0]
24         incr j $p
25     }
26 
27     while { 1 } {
28         incr p
29         if {[lindex $flags [expr {$p-1}]] == 1} { break }
30     }
31 }
32 
33 set sum 0
34 
35 for {set i 0} {$i < $n} {incr i} {
36     if {[lindex $flags $i] == 1} {
37         lappend garbage [expr {$i+1}]
38     }
39 }
40 
41 set length [llength $garbage]
42 
43 for {set i 0} {$i < $length} {incr i} {
44     incr sum [lindex $garbage $i]
45 }
46 
47 puts "sum = $sum"

VIM is absolutely wonderful when it comes to saving code into html. :)

Am început să ascult draconian prin 2004, cred… eram în anul I de facultate, deja începeam să-mi dau seama că nu tot ce zboară se mănîncă şi că în realitate dacă nu eşti pregătit să faci compromisuri, nu vei avea parte decît de dezamăgiri. Ascult şi acum draconian, sunt la fel de încăpăţînat, nu fac compromisuri, iar acest videoclip e superb… gothic doom at it’s best.

Chestii, trestii, wake up and hate. Cu ce să încep? Ah, desigur…

microbiştii lu’ peşte habar n-aveţi ce înseamnă psihologia unui meci important, cu miză mare, comentaţi şi înjuraţi ca proştii haha aţi luat ţeapă, vai ce dezamăgire, atîtea speranţe şi vise năruite => e numai vina voastră. Totul e numai vina voastră.

mă urc în maxi taxi vreau să-mi cumpăr bilet şoferu mă întreabă “da’ unde mergi băietu’?” “mă duc acasă. bilet, vă rog”. Nu ştiu cum e în alte oraşe dar aici în Iaşi fenomenul ăsta e exasperant. Noroc că mi-am făcut abonament pe toate liniile.

vacile “cul” care urlă în telefon în locuri publice ca să arate că au personalitate, howdy do missy, du-te şi behăie undeva pe cîmp de unde-ai venit. chiar zilele astea am întîlnit o personalitate din asta puternică, pînă să vină maxi taxi-le mi-am imaginat peste 50 de metode să-i fac praf cutia craniană. da, stiu, sunt foarte de treaba. nu, nu exagerez. “pentru că meritaţi”.

femeilor cu copchii mici care se urcă cu respectivele maimuţe în mijloace de transport ultra-aglomerate, sunteţi mai mult decît proaste, sunteţi iresponsabile şi inconştiente, iar apoi ajungeţi cu odraslele la veterinar. Ce stupid. Dar de fapt… selecţia naturală ar trebui să funcţioneze: cel mai nespălat cîştigă.

I’m sad coz’ my cat turned into a zombie. Beware!!

Să nu ziceţi că nu v-am avertizat.

Go placidly amid the noise and the haste,
and remember what peace there may be in silence.

As far as possible, without surrender,
be on good terms with all persons.
Speak your truth quietly and clearly;
and listen to others,
even to the dull and the ignorant;
they too have their story.
Avoid loud and aggressive persons;
they are vexatious to the spirit.

If you compare yourself with others,
you may become vain or bitter,
for always there will be greater and lesser persons than yourself.
Enjoy your achievements as well as your plans.
Keep interested in your own career, however humble;
it is a real possession in the changing fortunes of time.

Exercise caution in your business affairs,
for the world is full of trickery.
But let this not blind you to what virtue there is;
many persons strive for high ideals,
and everywhere life is full of heroism.
Be yourself. Especially do not feign affection.
Neither be cynical about love,
for in the face of all aridity and disenchantment,
it is as perennial as the grass.

Take kindly the counsel of the years,
gracefully surrendering the things of youth.
Nurture strength of spirit to shield you in sudden misfortune.
But do not distress yourself with dark imaginings.
Many fears are born of fatigue and loneliness.

Beyond a wholesome discipline,
be gentle with yourself.
You are a child of the universe
no less than the trees and the stars;
you have a right to be here.
And whether or not it is clear to you,
no doubt the universe is unfolding as it should.

Therefore be at peace with God,
whatever you conceive Him to be.
And whatever your labors and aspirations,
in the noisy confusion of life,
keep peace in your soul.

With all its sham, drudgery, and broken dreams,
it is still a beautiful world.
Be cheerful. Strive to be happy.

— Max Ehrmann

Dacă o vezi învîrtindu-se spre dreapta, înseamnă că îţi foloseşti (predominant) emisfera dreaptă a creierului, dacă o vezi învîrtindu-se spre stînga, îţi foloseşti emisfera stîngă. E posibil sa poti sa o vezi invartindu-se in ambele sensuri (evident nu simultan :P). In cazul asta te numeri printre “the select few” :).

Left brain functions: sequential, analytical, verbal, logical, linear algorithmic processing, mathematics: perception of counting/measurement, present and past, language: grammar/words, pattern perception, literal.

Right brain functions: simultaneous, holistic, imagistic, intuitive, holistical algorithm processing, mathematics: perception of shapes/motions, present and future, language: intonation/emphasis, prosody, pragmatic, contextual.

http://en.wikipedia.org/wiki/Cerebral_hemispheres

I was walking today, enjoying just being in motion, lost in thought, when suddenly somebody caught my arm, countering my inertia till my body came to a full halt. As I stopped, waiting patiently, curious about everything, I saw a man in his thirties or forties, staring at me with a madman’s gaze. Completely still. Frozen… he thought about the words he should speak, he did not know how, how to begin, how to say it, it was a secret hidden in his eyes. “My mum died”, said the man, as he trembled and wept like a little child, “could you please give me some directions?”. “Sure”, I said, looking at him, wondering how this must feel, and why he chose to share with me his great loss. “Where do you wish to go?”. My senses were telling me that the man had lost every notion of space and time and the world. I knew the place he told me about. “You should walk”, I said, “it’s not far”. I figured a walk would help him clear his mind. Completely calm and unemotional, I waited some seconds for him to let go and be on his way. And then, a moment of compassion…”I’m sorry”. I watched him walk away, his movement was almost seamless, he was in perfect balance with gravity. Where was he going? What is he going to do? Time will heal everything perhaps… humans are so strange. I should enjoy meeting that man again. I resumed my motion but my steps could never be as perfectly balanced as his. Not until…

No time, no more time…ain’t never enough time… I’m sick… I dream myself away.

Am examen mîine şi eu frec menta pe net… n-ar fi explus să-l pic… nu e un deznodămînd probabil dar cu siguranţă e foarte posibil. Ataraxie? Sau cum naiba să denumesc starea asta de somnolenţă şi nepăsare? Planificarea nu-ţi ajută cu nimic dacă nu eşti capabil de un singur impuls, o oarecare manifestare de voinţă şi ambiţie. Am conştiinţă? E încărcată? E vinovată? Nu. Fuck it, ce contează… I shall sleep. Dreaming power ballads :)

Rage - All this time

My reality is just different than yours! “In the mouth of madness“.

I’d like to live with You
In a small town,
Where there are eternal twilights
And eternal bells.
And in a small village inn—
The faint chime
Of ancient clocks—like droplets of time.
And sometimes, in the evenings, from some garret—
A flute,
And the flautist himself in the window.
And big tulips in the window-sills.
And maybe, You would not even love me…

In the middle of the room—a huge tiled oven,
On each tile—a small picture:
A rose—a heart—a ship.—
And in the one window—
Snow, snow, snow.

You would lie—thus I love You: idle,
Indifferent, carefree.
Now and then the sharp strike
Of a match.

The cigarette glows and burns down,
And trembles for a long, long time on its edge
In a gray brief pillar—of ash.
You’re too lazy even to flick it—
And the whole cigarette flies into the fire.

— Marina Tsvetaeva

Versuri superbe, destin tragic — http://english.tsvetayeva.com/biography. Timpul mutilează, apoi ucide.

To whom shall I speak today?
    I am laden with misery
    Through lack of an intimate …
Death is in my sight today
    Like the clearing of the sky,
    Like a man attracted thereby to
    What he knows not.

Death is in my sight today,
    Like the longing of a man to see home
    When he has spent many years held in
    captivity.

— Anonymous (a dispute over suicide, Egypt, before 2000 BC)