"""Converts a given 3x3 rotation matrix to intrinsic Euler angles in radians.

The function uses the XYZ convention for intrinsic Euler angles, which represents rotations around the X, Y, and Z axes in that order. The angles are returned in radians.

Parameters:
    rmat (np.array): A 3x3 rotation matrix.

Returns:
    np.array: A vector of three floats representing the intrinsic Euler angles (roll, pitch, yaw) in radians.
"""