Entry

Problems with frand()

Jul 5th, 2000 09:59
Nathan Wallace, Hans Nowak, Snippet 29, Daniel T.

"""
Packages: maths.random
"""

"""
With this post, I would like to do two things. A) Get critique on whether
I did well on my first Python program and B) see if someone can explain
why frand(0) never seems to return 0?

"""

# This code is a Python version of frand.c found in
# snip 9707

# The origional code was written by Larry Hudson

# Return random number in range (0.0, 1.0]                  #
#                                     #
# If n is negative it will randomize the seed, based on the #
#   current time.                                     #
# If n is zero it will return the next random number.       #
# If n is positive it will set the seed to a value based on #
#   the value of n.                                     #

from time import clock

TEN_PI = 31.41592653589793
E = 2.718281828459045
seed = E

def frand(n):
    " returns random number in range (0.0, 1.0]"

    global seed

    if n < 0:
        seed = clock() * E
    elif n > 0:
        seed = n * E
    else:
        seed = seed * TEN_PI + E
        seed = seed % 1
        return seed

###########################
lowest = 1
highest = 0

frand(-1)
for x in range(100000):
    y = frand(0)
    if y < lowest:
        lowest = y
    if y > highest:
        highest = y
print lowest, highest