pub trait MultilinearPoly<P: PackedField>: Debug {
// Required methods
fn n_vars(&self) -> usize;
fn log_extension_degree(&self) -> usize;
fn evaluate_on_hypercube(&self, index: usize) -> Result<P::Scalar, Error>;
fn evaluate_on_hypercube_and_scale(
&self,
index: usize,
scalar: P::Scalar,
) -> Result<P::Scalar, Error>;
fn evaluate(
&self,
query: MultilinearQueryRef<'_, P>,
) -> Result<P::Scalar, Error>;
fn evaluate_partial_low(
&self,
query: MultilinearQueryRef<'_, P>,
) -> Result<MultilinearExtension<P>, Error>;
fn evaluate_partial_high(
&self,
query: MultilinearQueryRef<'_, P>,
) -> Result<MultilinearExtension<P>, Error>;
fn subcube_inner_products(
&self,
query: MultilinearQueryRef<'_, P>,
subcube_vars: usize,
subcube_index: usize,
inner_products: &mut [P],
) -> Result<(), Error>;
fn subcube_evals(
&self,
subcube_vars: usize,
subcube_index: usize,
log_embedding_degree: usize,
evals: &mut [P],
) -> Result<(), Error>;
fn packed_evals(&self) -> Option<&[P]>;
// Provided method
fn size(&self) -> usize { ... }
}Expand description
Represents a multilinear polynomial.
This interface includes no generic methods, in order to support the creation of trait objects.
Required Methods§
sourcefn log_extension_degree(&self) -> usize
fn log_extension_degree(&self) -> usize
Binary logarithm of the extension degree (always exists because we only support power-of-two extension degrees)
sourcefn evaluate_on_hypercube(&self, index: usize) -> Result<P::Scalar, Error>
fn evaluate_on_hypercube(&self, index: usize) -> Result<P::Scalar, Error>
Get the evaluations of the polynomial at a vertex of the hypercube.
§Arguments
index- The index of the point, in lexicographic order
sourcefn evaluate_on_hypercube_and_scale(
&self,
index: usize,
scalar: P::Scalar,
) -> Result<P::Scalar, Error>
fn evaluate_on_hypercube_and_scale( &self, index: usize, scalar: P::Scalar, ) -> Result<P::Scalar, Error>
Get the evaluations of the polynomial at a vertex of the hypercube and scale the value.
This can be more efficient than calling evaluate_on_hypercube followed by a
multiplication when the trait implementation can use a subfield multiplication.
§Arguments
index- The index of the point, in lexicographic orderscalar- The scaling coefficient
fn evaluate( &self, query: MultilinearQueryRef<'_, P>, ) -> Result<P::Scalar, Error>
fn evaluate_partial_low( &self, query: MultilinearQueryRef<'_, P>, ) -> Result<MultilinearExtension<P>, Error>
fn evaluate_partial_high( &self, query: MultilinearQueryRef<'_, P>, ) -> Result<MultilinearExtension<P>, Error>
sourcefn subcube_inner_products(
&self,
query: MultilinearQueryRef<'_, P>,
subcube_vars: usize,
subcube_index: usize,
inner_products: &mut [P],
) -> Result<(), Error>
fn subcube_inner_products( &self, query: MultilinearQueryRef<'_, P>, subcube_vars: usize, subcube_index: usize, inner_products: &mut [P], ) -> Result<(), Error>
Compute inner products of a multilinear query inside a subcube.
Equivalent computation is evaluate_partial_low(query) followed by a subcube_evals
on a result. This method is more efficient due to handling it as a special case.
sourcefn subcube_evals(
&self,
subcube_vars: usize,
subcube_index: usize,
log_embedding_degree: usize,
evals: &mut [P],
) -> Result<(), Error>
fn subcube_evals( &self, subcube_vars: usize, subcube_index: usize, log_embedding_degree: usize, evals: &mut [P], ) -> Result<(), Error>
Get a subcube of the boolean hypercube of a given size.
Subcube of a multilinear is a set of evaluations $M(\beta_i\Vert x_j)$ , where
$\beta_i \in \mathcal{B}_k$ iterates over subcube_vars-sized hypercube and $x_j$ is a binary
representation of the subcube_index.
The result slice evals holds subcube evaluations in lexicographic order of $\beta_i$, with the
fastest stride corresponding to the first variable. Each scalar of the packed field P is assumed
to be a 2^log_embedding_degree extension field, where subcube evaluations are assigned to bases
in lexicographic order of the lowest log_embedding_degree variables.
Note that too large log_embedding_degree values may cause this method to fail.
sourcefn packed_evals(&self) -> Option<&[P]>
fn packed_evals(&self) -> Option<&[P]>
Returns the hypercube evaluations, embedded into packed extension field elements, if the data is already available.
This method is primarily used to access the raw evaluation data underlying a
MultilinearExtension that is type-erased as a MultilinearPoly trait object. The
evaluation data is useful for cases where the caller needs to dynamically re-interpret it
as subfield coefficients while avoiding copying, like for the small-field polynomial
commitment scheme or to provide directly to a hardware accelerator.
If the data is not available, this method returns None. If the data is available, it
should be interpreted not actually as a list of evaluations points given by iterating the
packed slice, but rather by iterating coefficients from a subfield with an embedding degree
given by Self::log_extension_degree.
The data returned, if Some, should be the same as the data that is written by
Self::subcube_evals.