tensor_variance.h

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//
// Copyright (c) 2014 Limit Point Systems, Inc. 
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//


#ifndef TENSOR_VARIANCE_H
#define TENSOR_VARIANCE_H

#ifndef SHEAF_DLL_SPEC_H
#include "SheafSystem/sheaf_dll_spec.h"
#endif

#ifndef STD_BITSET_H
#include "SheafSystem/std_bitset.h"
#endif

#ifndef STD_LIMITS_H
#include "SheafSystem/std_limits.h"
#endif

namespace fiber_bundle
{

class SHEAF_DLL_SPEC tensor_variance
{

  //==============================================================================
  //==============================================================================

public:

  tensor_variance();
  
  tensor_variance(const tensor_variance& xother);
  
  tensor_variance(int xp);

  ~tensor_variance();

  tensor_variance& operator=(const tensor_variance& xother);
  
  bool operator==(const tensor_variance& xother) const;

  static int capacity();

  int p() const;
  
  bool variance(int xi) const;
  
  void put_variance(int xi, bool xvalue);

  void put_variance(bool xvalue);

  bool is_covariant(int xi) const;

  bool is_covariant() const;

  bool is_contravariant(int xi) const;

  bool is_contravariant() const;

  bool is_mixed() const;

  bool is_pure() const;
  
  void purify();

protected:
private:
  
  int _p;
  
  typedef std::bitset<std::numeric_limits<unsigned long int>::digits> variance_type;

  variance_type _variance;
  
};

//==============================================================================
// NON-MEMBER FUNCTIONS
//==============================================================================

SHEAF_DLL_SPEC tensor_variance contract(const tensor_variance& x0, int xp, int xq);

SHEAF_DLL_SPEC tensor_variance tensor_product(const tensor_variance& x0, const tensor_variance& x1);

SHEAF_DLL_SPEC tensor_variance hook(const tensor_variance& x0);

SHEAF_DLL_SPEC tensor_variance star(const tensor_variance& x0, int xdd);

SHEAF_DLL_SPEC tensor_variance wedge(const tensor_variance& x0, const tensor_variance& x1);

SHEAF_DLL_SPEC tensor_variance raise(const tensor_variance& x0, int xi);

SHEAF_DLL_SPEC tensor_variance lower(const tensor_variance& x0, int xi);

} // namespace fiber_bundle


#endif // ifndef TENSOR_VARIANCE_H