Struct Mpie 

pub struct Mpie {
    pub iterations: usize,
    pub object_step: f64,
    pub stability: f64,
    pub momentum_interval: usize,
    pub momentum_friction: f64,
    pub momentum_feedback: f64,
    pub batch_size: usize,
    pub epsilon: f64,
    pub loss_type: LossType,
}

Momentum-accelerated regularized PIE adapted to image-plane FPM.

Method

Mpie applies the same sequential, object-only rPIE projection as super::Fpie, then periodically accelerates the centered high-resolution object spectrum. After momentum_interval positive-weight measured-frame updates, it updates the complex velocity and object as

V <- momentum_friction * V + (O_rpie - O_anchor)

O <- O_rpie + momentum_feedback * V.

A multiplexed measurement counts once after all of its source modes are inserted. Zero-weight frames do not advance the interval. The counter, velocity, anchor, and defining parameters are checkpointed, so changing batch_size does not change the numerical path and a matching checkpoint resumes exactly.

Adaptation and assumptions

The cited method was formulated and tested for scanned ptychography and applies momentum to both object and probe. This implementation accelerates only the fixed-pupil Fourier-ptychographic object spectrum. It separates the paper’s single eta_obj into friction and feedback controls; setting them equal reproduces its Eqs. (19) and (21). object_step corresponds to the paper’s gamma_obj in Eq. (22). Physical joint calibration is unsupported because recompiling the model would require an explicit rule for resetting or transporting momentum.

Reference

A. Maiden, D. Johnson, and P. Li, “Further improvements to the ptychographical iterative engine” (2017), Optica 4(7), 736–745.

Fields

iterations: usize

Number of complete passes through the acquisition schedule.

object_step: f64

Relaxation factor applied to each rPIE object-spectrum correction.

stability: f64

Blend between local pupil power (0) and maximum pupil power (1) in the rPIE denominator.

momentum_interval: usize

Positive-weight measured-frame updates between momentum events.

momentum_friction: f64

Fraction of the previous velocity retained at each momentum event.

momentum_feedback: f64

Fraction of the updated velocity added to the object spectrum.

batch_size: usize

Number of measured frames supplied to each reconstruction step.

epsilon: f64

Positive numerical floor added to the rPIE denominator.

loss_type: LossType

Loss used for diagnostics; the projection itself always enforces the measured amplitude.

Implementations

impl Mpie

pub fn iterations(self, iterations: usize) -> Self

Sets the number of complete acquisition-schedule passes.

pub fn object_step(self, object_step: f64) -> Self

Sets the finite positive relaxation applied to rPIE corrections.

pub fn stability(self, stability: f64) -> Self

Sets the rPIE pupil-power blend; validation requires [0, 1].

pub fn momentum_interval(self, momentum_interval: usize) -> Self

Sets the positive number of effective frame updates per momentum event.

pub fn momentum_friction(self, momentum_friction: f64) -> Self

Sets the retained-velocity fraction; validation requires [0, 1).

pub fn momentum_feedback(self, momentum_feedback: f64) -> Self

Sets the velocity-feedback fraction; validation requires [0, 1].

pub fn batch_size(self, batch_size: usize) -> Self

Sets the positive number of acquisition frames supplied per step.

pub fn epsilon(self, epsilon: f64) -> Self

Sets the finite positive numerical floor used by the rPIE denominator.

pub fn loss_type(self, loss_type: LossType) -> Self

Sets the loss reported by diagnostics.

Trait Implementations

impl Clone for Mpie

fn clone(&self) -> Mpie

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Mpie

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

Formats the value using the given formatter.

impl Default for Mpie

fn default() -> Self

Returns the “default value” for a type.

impl ReconstructionAlgorithm for Mpie

type IterationMetrics = NoIterationMetrics

Algorithm-specific metrics emitted by each step and appended to the trace.

fn validate(&self) -> Result<()>

Validates solver parameters independently of a reconstruction problem.

fn initialize<M: MeasurementRead>( &self, problem: &ReconstructionProblem<M>, ) -> Result<ReconstructionState>

Creates the default CPU-backed state for problem.

fn initialize_with_backend<M: MeasurementRead>( &self, problem: &ReconstructionProblem<M>, backend: Arc<dyn Backend>, ) -> Result<ReconstructionState>

Creates reconstruction state using the supplied execution backend.

fn supports_joint_reconstruction(&self) -> bool

Reports whether the algorithm may run inside physical joint calibration.

fn step<M: MeasurementRead>( &mut self, problem: &ReconstructionProblem<M>, state: &mut ReconstructionState, batch: &Batch, _iteration: usize, ) -> Result<StepOutput<Self::IterationMetrics>>

Updates state for one scheduled batch in zero-based iteration.

fn iterations(&self) -> usize

Returns the requested number of complete schedule passes.

fn batch_size(&self) -> usize

Returns the number of measured frames combined into one step.

fn validate_problem<M: MeasurementRead>( &self, _problem: &ReconstructionProblem<M>, ) -> Result<()>

Validates solver requirements that depend on problem.

fn canonicalize_state<M: MeasurementRead>( &self, _problem: &ReconstructionProblem<M>, _state: &mut ReconstructionState, ) -> Result<()>

Projects algorithm-owned ambiguities into a stable reported convention.

fn run<M: MeasurementRead>( self, problem: &ReconstructionProblem<M>, ) -> Result<ReconstructionResult>

where Self: Sized,

Runs the algorithm with default sequential scheduling and no callbacks.

fn run_with_callbacks<M: MeasurementRead>( self, problem: &ReconstructionProblem<M>, callbacks: Vec<Box<dyn Callback>>, ) -> Result<ReconstructionResult>

where Self: Sized,

Runs the algorithm and invokes callbacks at their declared hooks.

fn run_from_checkpoint<M: MeasurementRead>( self, problem: &ReconstructionProblem<M>, checkpoint: ReconstructionCheckpoint, ) -> Result<ReconstructionResult>

where Self: Sized,

Resumes a run from a checkpoint after validating it against problem.