factorial函数_带有Python示例的math.factorial（）方法

factorial函数

Python math.factorial()方法 (Python math.factorial() method)

math.factorial() method is a library method of math module, it is used to find the factorial of a given number, it accepts a positive integer number and returns the factorial of the number.

math.factorial()方法是数学模块的库方法，用于查找给定数字的阶乘，它接受正整数并返回数字的阶乘。

Note:

注意：

The method accepts only integer (positive) value, if the value is either a negative or float – it returns "ValueError".
该方法仅接受整数(正)值，如果该值是负数或浮点数，则返回“ ValueError” 。
If the number is 0 – its factorial will be 1.
如果数字为0 –其阶乘将为1。

Syntax of math.factorial() method:

math.factorial()方法的语法：

    math.factorial(n)

Parameter(s): n – a positive integer number.

参数： n-正整数。

Return value: int – it returns factorial of given number n.

返回值： int –返回给定数字n的阶乘。

Example:

例：

    Input:
    a = 6

    # function call
    print(math.factorial(a))

    Output:
    720

Python代码演示math.factorial()方法的示例 (Python code to demonstrate example of math.factorial() method)

# Python code to demonstrate example of 
# math.factorial() method

# importing math module
import math

# numbers
a = 0
b = 1
c = 6
d = 13

# printing factorial
print("factorial of ", a, " is = ", math.factorial(a))
print("factorial of ", b, " is = ", math.factorial(b))
print("factorial of ", c, " is = ", math.factorial(c))
print("factorial of ", d, " is = ", math.factorial(d))

Output

输出量

factorial of  0  is =  1
factorial of  1  is =  1
factorial of  6  is =  720
factorial of  13  is =  6227020800

ValueError: factorial() not defined for negative values

ValueError：factorial()未定义为负值

If we try to find the factorial of a negative integer value – method will return this error.

如果我们尝试找到负整数值的阶乘-方法将返回此错误。

# Python code to demonstrate example of 
# math.factorial() method

# importing math module
import math

# -ve integer 
a = -5

print(math.factorial(a))

Output

输出量

Traceback (most recent call last):
  File "/home/main.py", line 10, in <module>
    print(math.factorial(a))
ValueError: factorial() not defined for negative values

ValueError: factorial() only accepts integral values

ValueError：factorial()仅接受整数值

If we try to find the factorial of a float value – method will return this error.

如果我们尝试找到浮点值的阶乘-方法将返回此错误。

# Python code to demonstrate example of 
# math.factorial() method

# importing math module
import math

# -ve integer 
a = 5.1

print(math.factorial(a))

Output

输出量

Traceback (most recent call last):
  File "/home/main.py", line 10, in <module>
    print(math.factorial(a))
ValueError: factorial() only accepts integral values