Source code for mpt4py.functions.affine_function

import numpy as np
from typing import Optional
from .function_base import FunctionBase
from mpt4py.base import Matrix, Vector



class AffineFunction(FunctionBase):
	"""
	Class representing a (vector-valued) affine function of the form f(x) = Fx + g.
	"""
	def __init__(self, F: Matrix, g: Optional[Vector]):
		super().__init__()
		F = np.array(F)
		if np.ndim(F) != 2:
			raise ValueError("AffineFunction: F must be a matrix.")
		if g is None:
			g = np.zeros(F.shape[0])
		else:
			g = np.array(g).reshape((-1,))
		if np.ndim(g) != 1:
			raise ValueError("AffineFunction: g must be a vector.")
		self._F = np.array(F)
		self._g = np.array(g)

		self._lambda_expr = lambda x: self._F @ x + self._g



	def gradient(self, x: Vector) -> Vector:
		"""
		Compute the gradient of the affine function at a given point x.
		"""
		return self._F.T


	@property
	def F(self) -> Matrix:
		return self._F

	@property
	def g(self) -> Vector:
		return self._g