Happy PI day

By mauro, on Marzo 14th, 2008%

Hoy es 14 de Marzo, que escrito a la manera inglesa es 3.14. Today is π day!

Para festejarlo, nada mejor que estimar Pi de una manera original: Usando probabilidades.

Si tiramos una aguja al azar sobre una hoja de papel con líneas paralelas, separadas por una distancia igual al largo de la aguja, y contamos: N, la . . . → Read More: Happy PI day

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More Schneier facts

By mauro, on Marzo 3rd, 2008%

pi 29777 | tr 0-9 cneSuhrrBi
pi 31247517 | tr 0-9 hB\ nreuSci

See also:
- this post.
- More, diverse Bruce Schneier facts.
- hello world, regex powered.

~$ pi –bibliography
Recommended readings:
"Pi", by Joerg Arndt and Christoph Haenel (1999)
"Pi: A Source Book" by Lennart Berggren, Jonathan Borwein, Peter . . . → Read More: More Schneier facts

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Obfuscated hello world! (perl regex powered)

By mauro, on Junio 6th, 2007%

¿Cuáles son las 10 primeras cifras consecutivas no repetidas de los decimales de PI?
4592307816

echo "scale=100;a(1)*4" | bc -l | sed ‘:a;N;s/\\\n//;ta’ | \
perl -pe ‘s/.*?(.)(?!\1)(.)(?!\1|\2)(.)(?!\1|\2|\3)(.)(?!\1|\2|\3|\4)(.)(?!\1|\2|\3|\4|\5)(.)(?!\1|\2|\3|\4|\5|\6)(.)(?!\1|\2|\3|\4|\5|\6|\7)(.)(?!\1|\2|\3|\4|\5|\6|\7|\8)(.)(?!\1|\2|\3|\4|\5|\6|\7|\8|\9)(.).*/$1$2$3$4$5$6$7$8$9$10/’

¿Dónde en las cifras de PI está escondida la frase ‘Hello world’?
21463853067

Pues

$ echo 21463853067 | tr 0-9 reHolwld\
Hello world
$
echo "scale=4721;a(1)*4" | bc -l | sed ‘:a;N;s/\\\n//;ta’ | \
perl -pe ‘s/.*?(.)(?!\1)(.)(?!\1|\2)(.)(?!\1|\2)(.)(?!\1|\2|\3|\4)(.)(?!\1|\2|\3|\4|\5)(.)(?!\1|\2|\3|\4|\5|\6)(.)(?!\1|\2|\3|\4|\6|\7)(.)(?!\1|\2|\3|\4|\5|\6|\7|\8)(.)(?!\1|\2|\5|\6|\7|\8|\9)(.)(?!\1|\2|\3|\4|\5|\6|\7|\8|\9|\10)(.).*/$1$2$3$4$5$6$7$8$9$10$11/’ | . . . → Read More: Obfuscated hello world! (perl regex powered)

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