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import abc
import typing
from polymatrix.polymatrix.init import init_poly_matrix
from polymatrix.expression.mixins.expressionbasemixin import ExpressionBaseMixin
from polymatrix.polymatrix.abc import PolyMatrix
from polymatrix.expressionstate.abc import ExpressionState
from polymatrix.expression.utils.getderivativemonomials import differentiate_polynomial
from polymatrix.expression.utils.getvariableindices import (
get_variable_indices_from_variable,
)
from polymatrix.utils.getstacklines import FrameSummary
from polymatrix.utils.tooperatorexception import to_operator_exception
class DerivativeExprMixin(ExpressionBaseMixin):
"""
differentiate w.r.t. x:
[[x**2]] -> [[2*x]]
introduce_derivatives: not used at the moment
"""
@property
@abc.abstractmethod
def underlying(self) -> ExpressionBaseMixin: ...
@property
@abc.abstractmethod
def variables(self) -> ExpressionBaseMixin: ...
@property
@abc.abstractmethod
def introduce_derivatives(self) -> bool: ...
@property
@abc.abstractmethod
def stack(self) -> tuple[FrameSummary]: ...
# overwrites the abstract method of `ExpressionBaseMixin`
def apply(
self,
state: ExpressionState,
) -> tuple[ExpressionState, PolyMatrix]:
state, underlying = self.underlying.apply(state=state)
state, variables = get_variable_indices_from_variable(state, self.variables)
if not (underlying.shape[1] == 1):
raise AssertionError(
to_operator_exception(
message=f"{underlying.shape[1]=} is not 1",
stack=self.stack,
)
)
poly_matrix_data = {}
for row in range(underlying.shape[0]):
underlying_poly = underlying.get_poly(row, 0)
if underlying_poly is None:
continue
# derivate each variable and map result to the corresponding column
for col, variable in enumerate(variables):
state, diff_polynomial = differentiate_polynomial(
polynomial=underlying_poly,
diff_wrt_variable=variable,
state=state,
considered_variables=set(variables),
introduce_derivatives=self.introduce_derivatives,
)
if 0 < len(diff_polynomial):
poly_matrix_data[row, col] = diff_polynomial
poly_matrix = init_poly_matrix(
data=poly_matrix_data,
shape=(underlying.shape[0], len(variables)),
)
return state, poly_matrix
|
