fibodin.py

#!/usr/bin/env python
#
# Ask the user for:  m and n,
# Print out, the first  m  Fibonacci nunbers that are divisible by  n
# with no residue.
#
# Author:  Yotam Medini  [email protected] -- Created: 2005/June/06
#

import sys;    # For stdin/stdout and exit
import string  # To split the line

sys.stdout.write("""
Please enter two integer numbers  M and N,
and I will show you the first  M  Fibonacci numbers that
are divisible by N.
""")

user_line = sys.stdin.readline()
ul_split = string.split(user_line)
if len(ul_split) != 2:
    sys.stderr.write("Sorry I did not get two numbers\n")
    sys.exit(1)

# Take the separated strings
m_string = ul_split[0]
n_string = ul_split[1]

# Convert the strings to integer numbers
m = int(m_string)
n = int(n_string)


#########################################################
# Check the numbers.  We must have  m >= 0  and  n > 0. #
#########################################################

if m < 0:
    sys.stderr.write("You, yes YOU, owe me %d Fibonacci numbers\n" % -m)
    sys.exit(1)

if n == 0:
    sys.stderr.write("I will not even try to divide by ZERO!\n")
    sys.exit(1)

if n < 0:
    sys.stderr.write("Warning: n = %d < 0, I will use absolute |n| value\n"
                     % n)
    n = -n  # Now n > 0  and we forgive the user...

#######################################################
#  Finally - fight for Fibonacci fat numbers for fun  #
#######################################################

f1 = 0  # First Fibonacci number
f2 = 1  # Second Fibonacci number

found_count = 0  # How many found so far
while found_count < m:
    if f1 % n == 0:
        sys.stdout.write("Fibonacci number: %d\n" % f1)
        found_count = found_count + 1
    f3 = f1 + f2   # Next Fibonacci number
    f1 = f2        # We are done with old f1
    f2 = f3        # Make room for future

sys.stdout.write("For more Fibonacci numbers, run me again with new M,N\n")
sys.exit(0)