Source code for brainpy.integrators.fde.generic

# -*- coding: utf-8 -*-
# Copyright 2025 BrainX Ecosystem Limited. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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# ==============================================================================
from .base import FDEIntegrator

__all__ = [
    'set_default_fdeint',
    'get_default_fdeint',
    'register_fde_integrator',
    'get_supported_methods',
]

name2method = {}

_DEFAULT_DDE_METHOD = 'l1'




def fdeint(
    alpha,
    num_memory,
    inits,
    f=None,
    method='l1',
    dt: str = None,
    name: str = None
):
    """Numerical integration for FDEs.

    Parameters::

    f : callable, function
      The derivative function.
    method : str
      The shortcut name of the numerical integrator.
    alpha: int, float, jnp.ndarray, bm.ndarray, sequence
      The fractional-order of the derivative function. Should be in the range of ``(0., 1.]``.
    num_memory: int
      The number of the memory length.
    inits: sequence
      A sequence of the initial values for variables.
    dt: float, int
      The numerical precision.
    name: str
      The integrator name.

    Returns::

    integral : FDEIntegrator
        The numerical solver of `f`.
    """
    method = _DEFAULT_DDE_METHOD if method is None else method
    if method not in name2method:
        raise ValueError(f'Unknown FDE numerical method "{method}". Currently '
                         f'BrainPy supports: {list(name2method.keys())}')

    if f is None:
        return lambda f: name2method[method](f, dt=dt, name=name, inits=inits, num_memory=num_memory, alpha=alpha)
    else:
        return name2method[method](f, dt=dt, name=name, inits=inits, num_memory=num_memory, alpha=alpha)





def set_default_fdeint(method):
    """Set the default ODE numerical integrator method for differential equations.

    Parameters::

    method : str, callable
        Numerical integrator method.
    """
    if not isinstance(method, str):
        raise ValueError(f'Only support string, not {type(method)}.')
    if method not in name2method:
        raise ValueError(f'Unsupported ODE_INT numerical method: {method}.')

    global _DEFAULT_DDE_METHOD
    _DEFAULT_ODE_METHOD = method





def get_default_fdeint():
    """Get the default ODE numerical integrator method.

    Returns::

    method : str
        The default numerical integrator method.
    """
    return _DEFAULT_DDE_METHOD





def register_fde_integrator(name, integrator):
    """Register a new ODE integrator.

    Parameters::

    name: ste
      The integrator name.
    integrator: type
      The integrator.
    """
    if name in name2method:
        raise ValueError(f'"{name}" has been registered in FDE integrators.')
    if not issubclass(integrator, FDEIntegrator):
        raise ValueError(f'"integrator" must be an instance of {FDEIntegrator.__name__}')
    name2method[name] = integrator





def get_supported_methods():
    """Get all supported numerical methods for DDEs."""
    return list(name2method.keys())