provides an interface to
// kernel data structures.
type FS struct {
	proc fs.FS
}

// DefaultMountPoint is the common mount point of the proc filesystem.
const DefaultMountPoint = fs.DefaultProcMountPoint

// NewDefaultFS returns a new proc FS mounted under the default proc mountPoint.
// It will error if the mount point directory can't be read or is a file.
func NewDefaultFS() (FS, error) {
	return NewFS(DefaultMountPoint)
}

// NewFS returns a new proc FS mounted under the given proc mountPoint. It will error
// if the mount point directory can't be read or is a file.
func NewFS(mountPoint string) (FS, error) {
	fs, err := fs.NewFS(mountPoint)
	if err != nil {
		return FS{}, err
	}
	return FS{fs}, nil
}


// This file is part of Sophus.
//
// Copyright 2012-2013 Hauke Strasdat
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights  to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

#ifndef SOPHUS_SO2_HPP
#define SOPHUS_SO2_HPP

#include <complex>

#include "sophus.hpp"

////////////////////////////////////////////////////////////////////////////
// Forward De