Crate factorion_math 

Factorion Math

The math functions used by factorion. (Factorials and related functions) All functions that take Integers, but internally use Floats, not only have a float alternative, but also take in a precision.

This crate uses rug in its interface. It is re-exported for convenience.

Features

• k-factorials in exact, float, approximate, approximate digits
• termials in exact, float, approximate, approximate digits
• k-termials in exact, approximate, approximate digits
• subfactorials in exact, approximate, approximate digits

Calculations are split in areas:

• exact: integer calculation (accuracy)
• float: float calculation (decimals)
• approximate: approximation of integer calculation using float as a * 10^b (large numbers)
• approximate digits: approximation of integer calculation using float as 10^b (extremely large numbers)

Formulas and their derivations are available in MATH.md

Re-exports

pub use rug;

Modules

recommended

Recommended constants

Constants

APPROX_FACT_SAFE_UPPER_BOUND_FACTOR

Functions

adjust_approximate

Adjusts the output of approximate_factorial, by combining the 10 exponents of the number and the extra exponent.

approximate_approx_termial

The k-termial of x * 10^e as a * 10^b

approximate_factorial

Calculates Sterling’s Approximation of large factorials. Returns a float with the digits, and an int containing the extra base 10 exponent.

approximate_factorial_float

Calculates Sterling’s Approximation of large factorials. Returns a float with the digits, and an int containing the extra base 10 exponent.

approximate_multifactorial

Calculates an approximation of the multifactorial using the sterling aproximation and the fractional multifactorial algorithm.

approximate_multifactorial_digits

Calculates the approximate digits of a multifactorial. This is based on the base 10 logarithm of Sterling’s Approximation.

approximate_multifactorial_digits_float

Calculates the approximate digits of a multifactorial. This is based on the base 10 logarithm of Sterling’s Approximation.

approximate_multifactorial_float

Calculates an approximation of the multifactorial using the sterling aproximation and the fractional multifactorial algorithm.

approximate_subfactorial

The subfactorial of n as a * 10^b

approximate_subfactorial_float

The subfactorial of n as a * 10^b

approximate_termial

The k-termial of n as a * 10^b

approximate_termial_digits

The k-termial of n as 10^b

approximate_termial_digits_float

approximate_termial_float

The k-termial of n as a * 10^b

factorial

The k-factorial of n

fractional_factorial

The factorial of x (using gamma)

fractional_multifactorial

Calculates the k-factorial of x.

fractional_termial

The termial of x

length

Number of digits of n (log10, but 1 if 0)

multitermial

The k-termial of n

negative_multifacorial_factor

The k-factorial of -n is the factorial of n-k times this factor (inf if None)

subfactorial

The subfactorial of n

termial

The termial of n