sympy.stats.NegativeMultinomial() function in Python
Last Updated :
18 Aug, 2020
With the help of sympy.stats.NegativeMultinomial() method, we can create a discrete random variable with Negative Multinomial Distribution.
Syntax: sympy.stats.NegativeMultinomial(syms, k, p)
Parameters:
syms: the symbol
k: number of failures before the experiment is stopped, a positive integer
p: event probabilites, p>= 0 and p<= 1
Returns: a discrete random variable with Negative Multinomial Distribution.
Example #1 :
Python3
from sympy.stats import density
from sympy.stats.joint_rv_types import NegativeMultinomial
from sympy import symbols, pprint
p1, p2, p3 = symbols( 'p1, p2, p3' , positive = True )
x1, x2, x3 = symbols( 'x1, x2, x3' , nonnegative = True , integer = True )
N = NegativeMultinomial( 'N' , 3 , p1, p2, p3)
negMulti = density(N)(x1, x2, x3)
pprint(negMulti)
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Output :
x1 x2 x3 3
p1 *p2 *p3 *(-p1 - p2 - p3 + 1) *Gamma(x1 + x2 + x3 + 3)
-----------------------------------------------------------
2*x1!*x2!*x3!
Example #2 :
Python3
from sympy.stats import density
from sympy.stats.joint_rv_types import NegativeMultinomial
from sympy import symbols, pprint
x1, x2, x3 = symbols( 'x1, x2, x3' , nonnegative = True , integer = True )
N = NegativeMultinomial( 'N' , 2 , 1 / 3 , 1 / 2 )
negMulti = density(N)(x1, x2, x3)
pprint(negMulti)
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Output :
-x2 -x1
2 *3 *Gamma(x1 + x2 + x3 + 2)
---------------------------------
36*x1!*x
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