小间隔浮动的范围函数

set你在说

x += jump

这将x的值设置为2+1e-14,该值大于1e-2

当我读代码时,你的意思似乎是

myjump = pow(10, jump) #outside the loop

x *= myjump # inside the loop

这将在示例和过程1e-14、1e-12、1e-10…1e-2中将每个循环乘以100

或者,如果你想添加它,那么你应该说

x += myjump # inside the loop

或者你需要测试跳跃实际上是一个小到足以被处理的分数。

以下是一个已清理的版本:

def fn(x):
    return x * (x - 1)

def numerical_diff(fn, x, delta):
    return (fn(x + delta) - fn(x)) / delta

def geometric_series(a, r, n):
    value = a
    for i in range(n):
        yield value     # a * r ** i
        value *= r

def main():
    x = 1.
    for delta in geometric_series(0.01, 0.01, 7):
        print(
            "x = {:5.3f}  f(x) = {:5.3f}  delta = {:16.14f}  f'(x) = {:16.14f}"
            .format(x, fn(x), delta, numerical_diff(fn, x, delta))
        )

if __name__ == "__main__":
    main()

生产

x = 1.000  f(x) = 0.000  delta = 0.01000000000000  f'(x) = 1.01000000000000
x = 1.000  f(x) = 0.000  delta = 0.00010000000000  f'(x) = 1.00009999999989
x = 1.000  f(x) = 0.000  delta = 0.00000100000000  f'(x) = 1.00000099991773
x = 1.000  f(x) = 0.000  delta = 0.00000001000000  f'(x) = 1.00000000392253
x = 1.000  f(x) = 0.000  delta = 0.00000000010000  f'(x) = 1.00000008284037
x = 1.000  f(x) = 0.000  delta = 0.00000000000100  f'(x) = 1.00008890058334
x = 1.000  f(x) = 0.000  delta = 0.00000000000001  f'(x) = 0.99920072216265