# CS190C: Spring 2009
# Daniel Tang
# Problem Set 1, Problem 1
 
def main():
    print 'This program calculates the wind chill, given a temperature in'
    print 'degrees Fahrenheit and wind speed in miles per hour.'
    print
    t = input('Enter the temperature in degrees Fahrenheit: ')
    v = input('Enter the wind speed in miles per hour: ')
    # Calculate the wind chill w. This should mostly look like graphing
    # calculator syntax on the right-hand side of the equals sign. The only
    # thing new here is using ** as your exponent instead of ^.
    w = 35.74 + 0.6215*t + (0.4275*t - 35.75)*(v**0.16)
    print 'For a temperature of', t, 'and wind speed of', v, 'the wind chill is', w, 'degrees Fahrenheit.'
 
main()

# CS190C: Spring 2009
# Daniel Tang
# Problem Set 1, Problem 2
 
def main():
    print 'This program evaluates the first n terms of a geometric series.'
    print
    # Remember, it's possible to grab input for several variables at once.
    a, r, n = input('Enter a, r, n (for example "1, 2, 20"): ')
    # The accumulator variable should start at 0. If not, you have to handle
    # the case that n = 0 separately.
    total = 0
    # The current_ratio variable will keep track of the value of r^i. This is
    # cheaper than doing r**i for every iteration of the loop, since it only
    # requires one multiplication each time. It starts at 1 because r^0 = 1
    # regardless of r.
    current_ratio = 1
    # For some reason, many of you put "range(n+1)" or something like it. This
    # will evaluate n+1 terms instead of n.
    for i in range(n):
        # One trick to making this program more efficient is factoring out the
        # constant a and doing the multiplication after the loop (see below)
        total += current_ratio
        # After the below line is processed, current_ratio is r^(i+1). But this
        # is what we want, since it is the r^i value for the next iteration of
        # the loop.
        current_ratio *= r
 
    # At this point, total is r^0 + r^1 + ... + r^n. Now we multiply it by a
    # to get the total sum for the n terms we evaluated.
    total *= a
    print 'A geometric series with', n, 'terms with a =', a, 'and r =', r, 'evaluates to', total
 
main()