centered_diff.py 文件源码

def application():
    """makes list of the difference between the estimated derivative for h=0.01 and
    the analytical derivative"""
    application_list = []
    x = symbols('x')
    print
    print '%20s %20s' % ('Function', 'Error')
    print
    funcvar_tuples = [(lambda t: exp(t), 'exp(x)', float(0)), (lambda t : exp(-2*t**2), \
    'exp(-2*x**2)', float(0)), (lambda t: cos(t), 'cos(x)', 2*pi), (lambda t: log(t), \
    'log(x)', float(1))]
    for i in funcvar_tuples:
        prime = diff(i[1], x)
        exact = lambdify([x], prime)
        error = numdiff(i[0], i[2], 0.01) - exact(i[2])
        print '%20s %21.2E' % (i[1], error)
        print
        application_list.append(error)
    return application_list