Trampoline class for mfem::Operator. More...

#include <PyOperator.h>

Inheritance diagram for serif::pybind::PyOperator:

Public Member Functions
void	Mult (const mfem::Vector &x, mfem::Vector &y) const override
	Perform the operator action: y = A*x.

void	MultTranspose (const mfem::Vector &x, mfem::Vector &y) const override
	Perform the transpose operator action: y = A^T*x.

void	AddMult (const mfem::Vector &x, mfem::Vector &y, const mfem::real_t a=1.0) const override
	Perform the action y += a(Ax).

void	AddMultTranspose (const mfem::Vector &x, mfem::Vector &y, const mfem::real_t a=1.0) const override
	Perform the action y += a(A^Tx).

Operator &	GetGradient (const mfem::Vector &x) const override
	Get the gradient operator (Jacobian) at a given point x.

void	AssembleDiagonal (mfem::Vector &diag) const override
	Assemble the diagonal of the operator.

const mfem::Operator *	GetProlongation () const override
	Get the prolongation operator.

const mfem::Operator *	GetRestriction () const override
	Get the restriction operator.

void	RecoverFEMSolution (const mfem::Vector &X, const mfem::Vector &b, mfem::Vector &x) override
	Recover the FEM solution.

Detailed Description

Trampoline class for mfem::Operator.

This class allows Python classes to inherit from mfem::Operator and correctly override its virtual functions. When a virtual function is called from C++, the trampoline ensures the call is forwarded to the Python implementation if one exists. This is crucial for integrating Python-defined linear or non-linear operators into MFEM's C++-based solvers and algorithms.

See also: mfem::Operator

Python Usage Example:: import mfem.ser_ext as mfem

import numpy as np

class MyPythonOperator(mfem.Operator):

def __init__(self, size):

super().__init__(size) # Call the base C++ constructor

# Or super().__init__() if default constructing and setting height/width later

self.matrix = np.random.rand(size, size) # Example: store a dense matrix

# Must override Mult

def Mult(self, x, y):

# x is an mfem.Vector (input)

# y is an mfem.Vector (output, y = A*x)

# Ensure y is correctly sized if not already

if y.Size() != self.Height():

y.SetSize(self.Height())

# Example: y = self.matrix * x

# This is a conceptual illustration. For actual matrix-vector products

# with numpy, you'd convert mfem.Vector to numpy array or iterate.

x_np = x.GetDataArray() # Get a numpy view if configured

y_np = np.dot(self.matrix, x_np)

y.Assign(y_np) # Assign result back to mfem.Vector

print("MyPythonOperator.Mult called")

# Optionally override other methods like MultTranspose, GetGradient, etc.

def MultTranspose(self, x, y):

if y.Size() != self.Width():

y.SetSize(self.Width())

# Example: y = self.matrix.T * x

x_np = x.GetDataArray()

y_np = np.dot(self.matrix.T, x_np)

y.Assign(y_np)

print("MyPythonOperator.MultTranspose called")

# Using the Python operator

op_size = 5

py_op = MyPythonOperator(op_size)

x_vec = mfem.Vector(op_size)

x_vec.Assign(np.arange(op_size, dtype=float))

y_vec = mfem.Vector(op_size)

py_op.Mult(x_vec, y_vec)

print("Result y:", y_vec.GetDataArray())

# py_op can now be passed to MFEM functions expecting an mfem::Operator

Definition at line 83 of file PyOperator.h.

Member Function Documentation

◆ AddMult()

void serif::pybind::PyOperator::AddMult	(	const mfem::Vector &	x,
		mfem::Vector &	y,
		const mfem::real_t	a = 1.0 ) const

override

Perform the action y += a*(A*x).

Optional override.

Parameters

x	The input vector.
y	The vector to which a(Ax) is added.
a	Scalar multiplier (defaults to 1.0).

Note: This method forwards the call to the Python override if one exists.

Definition at line 33 of file PyOperator.cpp.

◆ AddMultTranspose()

void serif::pybind::PyOperator::AddMultTranspose	(	const mfem::Vector &	x,
		mfem::Vector &	y,
		const mfem::real_t	a = 1.0 ) const

override

Perform the action y += a*(A^T*x).

Optional override.

Parameters

x	The input vector.
y	The vector to which a(A^Tx) is added.
a	Scalar multiplier (defaults to 1.0).

Note: This method forwards the call to the Python override if one exists.

Definition at line 44 of file PyOperator.cpp.

◆ AssembleDiagonal()

void serif::pybind::PyOperator::AssembleDiagonal ( mfem::Vector & diag ) const

override

Assemble the diagonal of the operator.

For discrete operators (e.g., matrices), this method should compute and store the diagonal entries of the operator in the vector diag. Optional override.

Parameters

diag	Output vector to store the diagonal entries.

Note: This method forwards the call to the Python override if one exists.

Definition at line 64 of file PyOperator.cpp.

◆ GetGradient()

mfem::Operator & serif::pybind::PyOperator::GetGradient ( const mfem::Vector & x ) const

override

Get the gradient operator (Jacobian) at a given point x.

For non-linear operators, this method should return the linearization (Jacobian) of the operator at the point x. The returned Operator is owned by this Operator and should not be deleted by the caller. Optional override.

Parameters

x	The point at which to evaluate the gradient.

Returns: A reference to the gradient operator.

Note: This method forwards the call to the Python override if one exists.

Definition at line 55 of file PyOperator.cpp.

◆ GetProlongation()

const mfem::Operator * serif::pybind::PyOperator::GetProlongation ( ) const

override

Get the prolongation operator.

Used in multilevel methods (e.g., AMG). Returns a pointer to the prolongation operator (interpolation from a coarser level to this level). The returned Operator is typically owned by this Operator. Optional override.

Returns: A const pointer to the prolongation operator, or nullptr if not applicable.

Note: This method forwards the call to the Python override if one exists.

Definition at line 73 of file PyOperator.cpp.

◆ GetRestriction()

const mfem::Operator * serif::pybind::PyOperator::GetRestriction ( ) const

override

Get the restriction operator.

Used in multilevel methods (e.g., AMG). Returns a pointer to the restriction operator (projection from this level to a coarser level). Typically, this is the transpose of the prolongation operator. The returned Operator is typically owned by this Operator. Optional override.

Returns: A const pointer to the restriction operator, or nullptr if not applicable.

Note: This method forwards the call to the Python override if one exists.

Definition at line 81 of file PyOperator.cpp.

◆ Mult()

void serif::pybind::PyOperator::Mult	(	const mfem::Vector &	x,
		mfem::Vector &	y ) const

override

Perform the operator action: y = A*x.

This is a pure virtual function in mfem::Operator and must be overridden by any Python class inheriting from PyOperator.

Parameters

x	The input vector.
y	The output vector (result of A*x).

Note: This method forwards the call to the Python override. PYBIND11_OVERRIDE_PURE is used in the .cpp file to handle this.

Definition at line 8 of file PyOperator.cpp.

◆ MultTranspose()

void serif::pybind::PyOperator::MultTranspose	(	const mfem::Vector &	x,
		mfem::Vector &	y ) const

override

Perform the transpose operator action: y = A^T*x.

Optional override. If not overridden, MFEM's base implementation (which may raise an error or be a no-op) will be used.

Parameters

x	The input vector.
y	The output vector (result of A^T*x).

Note: This method forwards the call to the Python override if one exists. PYBIND11_OVERRIDE is used in the .cpp file to handle this.

Definition at line 23 of file PyOperator.cpp.

◆ RecoverFEMSolution()

void serif::pybind::PyOperator::RecoverFEMSolution	(	const mfem::Vector &	X,
		const mfem::Vector &	b,
		mfem::Vector &	x )

override

Recover the FEM solution.

For operators that are part of a system solve (e.g., static condensation), this method can be used to reconstruct the full finite element solution x from a reduced solution X and the right-hand side b. Optional override.

Parameters

X	The reduced solution vector.
b	The right-hand side vector.
x	Output vector for the full FEM solution.

Note: This method forwards the call to the Python override if one exists.

Definition at line 89 of file PyOperator.cpp.

The documentation for this class was generated from the following files:

src/python/mfem/Trampoline/PyMFEMTrampolines/Operator/PyOperator.h
src/python/mfem/Trampoline/PyMFEMTrampolines/Operator/PyOperator.cpp

Public Member Functions

Detailed Description

Member Function Documentation

◆ AddMult()

◆ AddMultTranspose()

◆ AssembleDiagonal()

◆ GetGradient()

◆ GetProlongation()

◆ GetRestriction()

◆ Mult()

◆ MultTranspose()

◆ RecoverFEMSolution()