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Adapt to mixed-mode arithmetic, and added a warning comment.

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This commit is contained in:
Guido van Rossum 1991-12-18 13:45:17 +00:00
parent 97dddba1bb
commit 1c8230b70d
1 changed files with 8 additions and 6 deletions
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14
Demo/scripts/fact.py
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@ -1,7 +1,9 @@
#! /usr/local/python #! /usr/local/python
# Factorize numbers, slowly. # Factorize numbers.
# This version uses plain integers and is thus limited to 2**31-1. # The algorithm is not efficient, but easy to understand.
# If there are large factors, it will take forever to find them,
# because we try all odd numbers between 3 and sqrt(n)...
import sys import sys
from math import sqrt from math import sqrt
@ -17,13 +19,13 @@ def fact(n):
res.append(2) res.append(2)
n = n/2 n = n/2
# Try odd numbers up to sqrt(n) # Try odd numbers up to sqrt(n)
limit = int(sqrt(float(n+1))) limit = sqrt(n+1)
i = 3 i = 3
while i <= limit: while i <= limit:
if n%i = 0: if n%i = 0:
res.append(i) res.append(i)
n = n/i n = n/i
limit = int(sqrt(float(n+1))) limit = sqrt(n+1)
else: else:
i = i+2 i = i+2
res.append(n) res.append(n)
@ -32,12 +34,12 @@ def fact(n):
def main(): def main():
if len(sys.argv) > 1: if len(sys.argv) > 1:
for arg in sys.argv[1:]: for arg in sys.argv[1:]:
n = int(eval(arg)) n = eval(arg)
print n, fact(n) print n, fact(n)
else: else:
try: try:
while 1: while 1:
n = int(input()) n = input()
print n, fact(n) print n, fact(n)
except EOFError: except EOFError:
pass pass