Trait argmin::core::CostFunction

pub trait CostFunction {
    type Param;
    type Output;

    // Required method
    fn cost(&self, param: &Self::Param) -> Result<Self::Output, Error>;

    // Provided methods
    fn bulk_cost<P>(&self, params: &[P]) -> Result<Vec<Self::Output>, Error>
       where P: Borrow<Self::Param> + SyncAlias,
             Self::Output: SendAlias,
             Self: SyncAlias { ... }
    fn parallelize(&self) -> bool { ... }
}

Defines computation of a cost function value

Example

use argmin::core::{CostFunction, Error};
use argmin_testfunctions::rosenbrock;

struct Rosenbrock {}

impl CostFunction for Rosenbrock {
    type Param = Vec<f64>;
    type Output = f64;

    /// Compute Rosenbrock function
    fn cost(&self, param: &Self::Param) -> Result<Self::Output, Error> {
        Ok(rosenbrock(param))
    }
}

Required Associated Types

type Param

Type of the parameter vector

type Output

Type of the return value of the cost function

Required Methods

fn cost(&self, param: &Self::Param) -> Result<Self::Output, Error>

Compute cost function

Provided Methods

fn bulk_cost<P>(&self, params: &[P]) -> Result<Vec<Self::Output>, Error>

where P: Borrow<Self::Param> + SyncAlias, Self::Output: SendAlias, Self: SyncAlias,

Compute cost in bulk. If the rayon feature is enabled, multiple calls to cost will be run in parallel using rayon, otherwise they will execute sequentially. If the rayon feature is enabled, parallelization can still be turned off by overwriting parallelize to return false. This can be useful in cases where it is preferable to parallelize only certain parts. Note that even if parallelize is set to false, the parameter vectors and the problem are still required to be Send and Sync. Those bounds are linked to the rayon feature. This method can be overwritten.

fn parallelize(&self) -> bool

Indicates whether to parallelize calls to cost when using bulk_cost. By default returns true, but can be set manually to false if needed. This allows users to turn off parallelization for certain traits implemented on their problem. Note that parallelization requires the rayon feature to be enabled, otherwise calls to cost will be executed sequentially independent of how parallelize is set.

Object Safety

This trait is not object safe.

Implementors

impl CostFunction for TestProblem

type Param = Vec<f64>

type Output = f64

impl CostFunction for TestSparseProblem

type Param = Vec<f64>

type Output = f64