Source code for pina.equation.equation
"""Module for the Equation."""
import inspect
from .equation_interface import EquationInterface
[docs]
class Equation(EquationInterface):
"""
Implementation of the Equation class. Every ``equation`` passed to a
:class:`~pina.condition.condition.Condition` object must be either an
instance of :class:`Equation` or
:class:`~pina.equation.system_equation.SystemEquation`.
"""
def __init__(self, equation):
"""
Initialization of the :class:`Equation` class.
:param Callable equation: A ``torch`` callable function used to compute
the residual of a mathematical equation.
:raises ValueError: If the equation is not a callable function.
"""
if not callable(equation):
raise ValueError(
"equation must be a callable function."
"Expected a callable function, got "
f"{equation}"
)
# compute the signature
sig = inspect.signature(equation)
self.__len_sig = len(sig.parameters)
self.__equation = equation
[docs]
def residual(self, input_, output_, params_=None):
"""
Compute the residual of the equation.
:param LabelTensor input_: Input points where the equation is evaluated.
:param LabelTensor output_: Output tensor, eventually produced by a
:class:`torch.nn.Module` instance.
:param dict params_: Dictionary of unknown parameters, associated with a
:class:`~pina.problem.inverse_problem.InverseProblem` instance.
If the equation is not related to a
:class:`~pina.problem.inverse_problem.InverseProblem` instance, the
parameters must be initialized to ``None``. Default is ``None``.
:return: The computed residual of the equation.
:rtype: LabelTensor
:raises RuntimeError: If the underlying equation signature length is not
2 (direct problem) or 3 (inverse problem).
"""
if self.__len_sig == 2:
return self.__equation(input_, output_)
if self.__len_sig == 3:
return self.__equation(input_, output_, params_)
raise RuntimeError(
f"Unexpected number of arguments in equation: {self.__len_sig}. "
"Expected either 2 (direct problem) or 3 (inverse problem)."
)