from typing import List
import numpy as np

class YourClass:
    
    @staticmethod
    def _reprojection_error(mask: List[bool], M: np.ndarray, src_pts: np.ndarray, dst_pts: np.ndarray) -> float:
        """
        Computes the reprojection error between the source and destination points.

        Args:
        - mask (List[bool]): A list of boolean values indicating whether to use each point pair for the calculation.
        - M (np.ndarray): A 3x4 projection matrix that maps points from the source image to the destination image.
        - src_pts (np.ndarray): An Nx2 array containing the source points.
        - dst_pts (np.ndarray): An Nx2 array containing the destination points.

        Returns:
        - error (float): The reprojection error.
        """
        num_points = np.sum(mask)
        src_pts_3d = np.hstack((src_pts, np.ones((src_pts.shape[0], 1))))
        dst_pts_3d = np.hstack((dst_pts, np.ones((dst_pts.shape[0], 1))))
        projected_dst_pts_3d = M @ src_pts_3d.T
        projected_dst_pts_2d = (projected_dst_pts_3d[:2, :] / projected_dst_pts_3d[2, :]).T
        error_per_point = np.sqrt(np.sum((dst_pts[mask] - projected_dst_pts_2d[mask])**2, axis=1))
        error = np.sum(error_per_point) / num_points
        return error