Enum Jacobian 

pub enum Jacobian {
    Exact,
    MaxLog,
}

The Jacobian logarithm of the log-MAP algorithms and of the soft demappers, exact or approximated by its maximum:

$$ \ln\left(e^{a} + e^{b}\right) = \max(a, b) + \ln\left(1 + e^{-\lvert a - b \rvert}\right) \approx \max(a, b). $$

One choice for Demap (Demapping::jacobian), max_star of comnum-math (which re-exports it as comnum_math::Jacobian), the BCJR and turbo decoders of comnum-fec and the demappers of comnum-mapping; a specification keeps the boolean key max_log (Jacobian::from_max_log).

Variants

Exact

The exact logarithm (log-MAP, log-sum-exp).

MaxLog

The max-log approximation, $\max(a, b)$.

Implementations

impl Jacobian

pub fn from_max_log(max_log: bool) -> Jacobian

Jacobian::MaxLog when max_log is true, Jacobian::Exact otherwise (the boolean key max_log of the specifications and of the Python API).

Examples

use comnum_core::traits::Jacobian;
assert_eq!(Jacobian::from_max_log(true), Jacobian::MaxLog);
assert_eq!(Jacobian::from_max_log(false), Jacobian::default());

pub fn is_exact(self) -> bool

Whether the logarithm is exact.

Trait Implementations

impl Clone for Jacobian

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Jacobian

impl Debug for Jacobian

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Jacobian

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Jacobian

impl Hash for Jacobian

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Jacobian

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Jacobian