Abstract constrained minimizer added

bqskit/ir/opt/constrained.py

@@ -0,0 +1,48 @@
+"""This module implements the Minimizer base class."""
+from __future__ import annotations
+
+import abc
+from typing import TYPE_CHECKING
+
+import numpy as np
+import numpy.typing as npt
+
+from bqskit.qis.unitary.unitary import RealVector
+
+if TYPE_CHECKING:
+    from bqskit.ir.opt.cost.function import CostFunction
+
+
+class ConstrainedMinimizer(abc.ABC):
+    """
+    The Minimizer class.
+
+    An minimizer finds the parameters for a circuit template that minimizes some
+    CostFunction.
+    """
+
+    @abc.abstractmethod
+    def constrained_minimize(
+        self,
+        cost: CostFunction,
+        cstr: CostFunction,
+        x0: RealVector,
+    ) -> npt.NDArray[np.float64]:
+        """
+        Minimize `cost` starting from initial point `x0` while obeying `cstr`.
+
+        Args:
+            cost (CostFunction): The CostFunction to minimize.
+
+            cstr (CostFunction): The CostFunction used to constrain solutions.
+
+            x0 (np.ndarray): The initial point.
+
+        Returns:
+            (np.ndarray): The inputs that best minimizes the cost while obeying
+                the constraints.
+
+        Notes:
+            This function should be side-effect free. This is because many
+            calls may be running in parallel.
+        """