Python | sympy.ff() method

With the help of sympy.ff() method, we can find the Falling factorial. Falling factorial is defined by –

where x can be arbitrary expression and k is an integer.

Syntax: ff(x, k) Parameter: x – It denotes any arbitrary expression. k – It denotes an integer. Returns: Returns falling factorial corresponding to the given inputs.

Example #1:

# import sympy
from sympy import *

x = symbols('x')
k = 5
print("Value of x = {} and k = {}".format(x, k))

# Use sympy.ff() method
ff_x_k = ff(x, k)

print("Falling factorial ff(x, k) : {}".format(ff_x_k))

Output:

Value of x = x and k = 5
Falling factorial ff(x, k) : x*(x - 4)*(x - 3)*(x - 2)*(x - 1)

Example #2:

# import sympy
from sympy import * x = 7
k = 5
print("Value of x = {} and k = {}".format(x, k))

# Use sympy.ff() method
ff_x_k = ff(x, k)

print("Falling factorial ff(x, k) : {}".format(ff_x_k))

Output:

Value of x = 7 and k = 5
Falling factorial ff(x, k) : 2520