perazz / fortran-primes

A tiny Fortran library for evaluating and using prime numbers

fortran-primes

This is a tiny Modern Fortran library for handling prime numbers. The base code was spun off the FRESCO CFD code, while additional functions are modern Fortran ports of codes from Michal Forisek, David Deley and Primes.jl.

API

function	type	Description
prime(n)	integer(IP), integer(WP)	Returns the $n$-th prime number.
primes(n)	integer(IP)	Returns a list containing all primes in the range $1 \lt p_i \le n$.
primes(lo,hi)	integer(IP)	Returns a list containing all primes in the range $L \le p_i \le H$.
is_prime(n)	logical(LP)	Boolean flag to check if $n$ is a prime number.
primes_mask(n)	logical(LP)	Logical mask ranged (1:n) flagging the prime numbers in the range from 1 to n.
primes_mask(lo,hi)	logical(LP)	Logical mask ranged (1:hi-lo+1) flagging the prime numbers in the range from lo to hi.
next_prime(n)	integer(IP)	Returns the first prime number p_i > n
next_prime(n,i)	integer(IP)	Returns the $i$-th ($i \ge 1$) prime number larger than $n$.
prime_factors(n,f)	integer(IP)	Returns all prime factors, and their multiplicities, of an integer. for example, $90=2\cdot3^2\cdot5$. prime_factors(90,f) returns f(:,1) = [2,1], f(:,2) = [3,2], f(:,3) = [5,1].

Building, using

An automated build is available via the Fortran Package Manager. To use fortran-primes within your FPM project, add the following to your fpm.toml file:

[dependencies]
fortran-primes = { git="https://github.com/perazz/fortran-primes.git" }