eigen_utils.h

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/*

Copyright (c) 2010, Stephan Weiss, ASL, ETH Zurich, Switzerland
You can contact the author at <stephan dot weiss at ieee dot org>

All rights reserved.

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modification, are permitted provided that the following conditions are met:
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* Redistributions in binary form must reproduce the above copyright
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* Neither the name of ETHZ-ASL nor the
names of its contributors may be used to endorse or promote products
derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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*/

#ifndef EIGEN_UTILS_H_
#define EIGEN_UTILS_H_

#include <Eigen/Dense>
#include <Eigen/Geometry>

template<class Derived>
  inline Eigen::Matrix<typename Derived::Scalar, 3, 3> skew(const Eigen::MatrixBase<Derived> & vec)
  {
    EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived, 3);
    return (Eigen::Matrix<typename Derived::Scalar, 3, 3>() << 0.0, -vec[2], vec[1], vec[2], 0.0, -vec[0], -vec[1], vec[0], 0.0).finished();
  }


template<class Derived>
  inline Eigen::Matrix<typename Derived::Scalar, 4, 4> omegaMatJPL(const Eigen::MatrixBase<Derived> & vec)
  {
    EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived, 3);
    return (
        Eigen::Matrix<typename Derived::Scalar, 4, 4>() <<
        0, vec[2], -vec[1], vec[0],
        -vec[2], 0, vec[0], vec[1],
        vec[1], -vec[0], 0, vec[2],
        -vec[0], -vec[1], -vec[2], 0
        ).finished();
  }


template<class Derived>
  inline Eigen::Matrix<typename Derived::Scalar, 4, 4> omegaMatHamilton(const Eigen::MatrixBase<Derived> & vec)
  {
    EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived, 3);
    return (
        Eigen::Matrix<typename Derived::Scalar, 4, 4>() <<
        0, -vec[2], vec[1], vec[0],
        vec[2], 0, -vec[0], vec[1],
        -vec[1], vec[0], 0, vec[2],
        -vec[0], -vec[1], -vec[2], 0
        ).finished();
  }

template<class Derived>
  Eigen::Quaternion<typename Derived::Scalar> quaternionFromSmallAngle(const Eigen::MatrixBase<Derived> & theta)
  {
  typedef typename Derived::Scalar Scalar;
  EIGEN_STATIC_ASSERT_FIXED_SIZE(Derived);
  EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived, 3);
  const Scalar q_squared = theta.squaredNorm() / 4.0;

    if ( q_squared < 1)
    {
      return Eigen::Quaternion<Scalar>(sqrt(1 - q_squared), theta[0] * 0.5, theta[1] * 0.5, theta[2] * 0.5);
    }
    else
    {
      const Scalar w = 1.0 / sqrt(1 + q_squared);
      const Scalar f = w*0.5;
      return Eigen::Quaternion<Scalar>(w, theta[0] * f, theta[1] * f, theta[2] * f);
    }
  }

template<class T>
  bool checkForNumeric(const T & vec, int size, const std::string & info)
  {
    for (int i = 0; i < size; i++)
    {
      if (isnan(vec[i]))
      {
        std::cerr << "=== ERROR ===  " << info << ": NAN at index " << i << std::endl;
        return false;
      }
      if (isinf(vec[i]))
      {
        std::cerr << "=== ERROR ===  " << info << ": INF at index " << i << std::endl;
        return false;
      }
    }
    return true;
  }

#endif /* EIGEN_UTILS_H_ */