# Prime functions in Python SymPy

How to get prime numbers quickly in python using library functions ?

Library functions always makes our code easy so here we are going to discuss some library function in python to work upon prime numbers. SymPy is a python module which contains some really cool prime number related library functions. Given below is the list of these functions :

1. isprime(n) : It tests if n is a prime number (True) or not (False).
2. primerange(a, b) : It generates a list of all prime numbers in the range [a, b).
3. randprime(a, b) : It returns a random prime number in the range [a, b).
4. primepi(n) : It returns the number of prime numbers less than or equal to n.
5. prime(nth) : It returns the nth prime, with the primes indexed as prime(1) = 2. The nth prime is approximately n*log(n) and can never be larger than 2**n.
6. prevprime(n) : It returns the prev prime smaller than n.
7. nextprime(n) : It returns the next greater prime than n.
8. sieve.primerange(a, b) : It generates all prime numbers in the range [a, b), implemented as a dynamically growing sieve of Eratosthenes.
 ` `
`# Library functions for prime`
`import` `sympy`
`# Output : True`
`print` `sympy.isprime(``5``)                        `
`# Output : [2, 3, 5, 7, 11, 13, 17, 19, 23, `
`# 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, `
`# 73, 79, 83, 89, 97]`
`print` `list``(sympy.primerange(``0``, ``100``))      `
`    `
`print` `sympy.randprime(``0``, ``100``)  ``# Output : 83`
`print` `sympy.randprime(``0``, ``100``)  ``# Output : 41`
`print` `sympy.prime(``3``)           ``# Output : 5`
`print` `sympy.prevprime(``50``)      ``# Output : 47`
`print` `sympy.nextprime(``50``)      ``# Output : 53`
`# Output : [2, 3, 5, 7, 11, 13, 17, 19, 23, 29,`
`# 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, `
`# 79, 83, 89, 97]`
`print` `list``(sympy.sieve.primerange(``0``, ``100``))`

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source and credits.
source and credits: http://www.geeksforgeeks.org
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