مهندسی نرم افزار و کارگاه عمومی

def squareRootBi(x,epsilon):

    '''Assume x>= 0 and epsilon > 0

        Return y s.t. y*y is close enough to x'''

    assert x>=0, 'input should be nonnegative number, not' + str(x)

    assert epsilon > 0, 'epsilon should be positive number, not' + str(epsilon)

    low = 0 # lower bound of searching range 

    high = max(1,x) # upper bound of  searching range

    guess = (low+high)/2.0

    ctr = 1

    while abs(guess**2-x)>epsilon and ctr <=100:

        #print 'low:',low,'high:',high,'guess:',guess

        if guess**2 < x:

            low = guess

        else:

            high = guess

        guess = (low+high)/2.0

        ctr += 1

    assert ctr <= 100, 'Iteration exceeded'

    print 'Bi method. Num. Iteration:',ctr,'Estimate:',guess

    return guess

def testBi():

    print 'squareRootBi(4,0.0001)'

    squareRootBi(4,0.0001)

    print 'squareRootBi(9,0.0001)'

    squareRootBi(9,0.0001)

    print 'squareRootBi(2,0.0001)'

    squareRootBi(2,0.0001)

    print 'squareRootBi(0.25,0.0001)'

    squareRootBi(0.25,0.0001)

def squareRootNR(x,epsilon):

    '''Assume x>= 0 and epsilon > 0

        Return y s.t. y*y is close enough to x'''

    assert x>=0, 'input should be nonnegative number, not' + str(x)

    assert epsilon > 0, 'epsilon should be positive number, not' + str(epsilon)

    x = float(x)

    guess = x/2.0

##    guess = 0.01

    diff = guess**2 - x

    ctr = 1

    while abs(diff) > epsilon and ctr<=100:

        guess = guess - diff/(2.0*guess)

        diff = guess**2 - x

        ctr += 1

    assert ctr <= 100, 'Iteration exceeded'

    print 'NR method. Num. Iteration:',ctr,'Estimate:',guess

    return guess