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Jaime Soffer jsoffer

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jsoffer / gist:1284803
Created October 13, 2011 17:03
/* archivo, test.c */
#include <stdio.h>
void main () {
char c;
c = c & 0;
printf("The value of c is %d", (int)c);
int j = 255;
c = (c | j);
@jsoffer
jsoffer / gist:875648
Created March 18, 2011 05:07
Recurrencia a(n+2) + 2*a(n+1) + 2*a(n) = 0, n >= 0, a(0) = 1, a(1) = 3
[GP] (recuperando las raíces)
? polroots(x^2+2*x+2)
%1 = [-1.000000000000000000000000000 - 1.000000000000000000000000000*I, -1.000000000000000000000000000 + 1.000000000000000000000000000*I]~
[Haskell]
(construyendo la recurrencia directamente)
@jsoffer
jsoffer / gist:862100
Created March 9, 2011 12:17
PARI/GP
La serie formal generada por (3*x^2 + 5)/((1-x^2)*(1-x)^2) hasta x^99, el O(x^n)
representa el error y al sumarlo GP entiende que es serie en lugar de solamente
función racional
? p = (3*x^2 + 5)/((1-x^2)*(1-x)^2) + O(x^100)
Extrae el coeficiente de x^45
@jsoffer
jsoffer / gist:846667
Created February 27, 2011 23:02
-- CollatzBool.hs
module CollatzBool where
porTresMasUno :: [Bool] -> [Bool]
porTresMasUno xs = False : ys ++ residuo where
cs = True : zipWith3 gc cs (tail xs) xs
gc b = if b then (||) else (&&)
ys = zipWith3 gy cs (tail xs ++ [False]) xs
gy p q r = (p /= q) /= r
@jsoffer
jsoffer / gist:846151
Created February 27, 2011 12:42
porTresMasUno :: [Bool] -> [Bool]
porTresMasUno xs = False : ys ++ residuo where
cs = True : zipWith3 gc cs (tail xs) xs
gc b = if b then (||) else (&&)
ys = zipWith3 gy cs (tail xs ++ [False]) xs
gy p q r = (p /= q) /= r
residuo = if last cs then [True] else []
serie :: String -> [[Bool]]
serie s = takeWhile (not.alto) $ iterate paso $ leer s where
@jsoffer
jsoffer / gist:844640
Created February 25, 2011 22:35
-- head = LSB
decimal_a_bool :: Integer -> [Bool]
decimal_a_bool 1 = [True]
decimal_a_bool n = odd n : decimal_a_bool (div n 2)
bool_a_decimal :: [Bool] -> Integer
-- La cadena vacía no tiene representación
bool_a_decimal [] = error "Sin entrada"
@jsoffer
jsoffer / gist:802466
Created January 30, 2011 02:47
-- LFSR, en formato compatible con
-- http://homepage.mac.com/afj/taplist.html
-- uso (en ghci):
-- > let t = ciclo 7 $ drop 7 $ leer $ generar "1111111" [7,6,4,2]
-- "1111111" es cadena inicial con 7 registros
-- [7, 6, 4, 2] es cuarteta en http://homepage.mac.com/afj/7bits.txt
-- 'ciclo 7' se detiene cuando se repite la secuencia de los 7 primeros símbolos
-- > t
-- "00111110110111000000101000011011
@jsoffer
jsoffer / gist:800359
Created January 28, 2011 15:09
zipWithN f = foldl1 (zipWith f)
generar :: String -> [Int] -> [Bool]
generar inicial indices = ts where
ts = xs ++ zipWithN (/=) (g indices)
xs = map (== '1') inicial
g = map ((flip drop) ts)
leer n xs = take n $ map (\k -> if k then '1' else '0') xs
@jsoffer
jsoffer / gist:798568
Created January 27, 2011 14:28
-- Como recurrencias, operando sobre listas infinitas paralelas
-- con función x1 + x3
t1 = True : False : False : True : zipWith (/=) (drop 1 t1) (drop 3 t1)
-- x1 + x2 + x3
t2 = True : False : False : True : zipWith3 g (drop 1 t2) (drop 2 t2) (drop 3 t2) where
g a b c = (a /= b) /= c
leer n xs = take n $ map (\k -> if k then '1' else 0') xs
@jsoffer
jsoffer / gist:786484
Created January 19, 2011 17:23
takeUntil :: (a -> Bool) -> [a] -> [a]
takeUntil _ [] = []
takeUntil p (x:xs)
| (not.p) x = x : takeUntil p xs
| otherwise = [x]
paso :: (Integer, Integer, Integer, Integer) -> (Integer, Integer, Integer, Integer)
paso (numimpares,secuencia,x,reg) = (numimpares',secuencia',x',reg') where
x' = quot x 2
corregido = if odd x then reg + 3^numimpares else reg