# Problem 7B
#
# Create a generally smooth gradation of white to 
# black, from left to right using only a 100 percent black pen

import math

g.paper(0)
g.pen(100)
g.norefresh()

distribution = []
for n in range(102):
        distribution.append(0)

def spiraller(xc, yc, radius, turns, points, array=distribution):
    for n in range(points):
        x = int(xc + float(n)/points*radius*math.cos(turns*float(n)/points))
        y = int(yc + float(n)/points*radius*math.sin(turns*float(n)/points))
        if n % 2 == 0:
                if x < 102 and x > -1 and y > -1 and y < 102 and array[x] < x:
                        array[x] = array[x] + 1
                        g.setPixel(x,y,100)

while 1:
        n = n+1 
        spiraller(110,50,120,n%50,n)
        g.refresh()
        #g.paper(0)