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diff --git a/include/gudhi/writing_persistence_to_file.h b/include/gudhi/writing_persistence_to_file.h
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+/*    This file is part of the Gudhi Library. The Gudhi library
+ *    (Geometric Understanding in Higher Dimensions) is a generic C++
+ *    library for computational topology.
+ *
+ *    Author(s):       Pawel Dlotko
+ *
+ *    Copyright (C) 2017  Swansea University, UK
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef WRITING_PERSISTENCE_TO_FILE_H_
+#define WRITING_PERSISTENCE_TO_FILE_H_
+
+#include <iostream>
+#include <string>
+#include <limits>
+
+namespace Gudhi {
+
+/**
+* This is a class to store persistence intervals. Its main purpose is to
+* exchange data in between different packages and provide unified way
+* of writing a collection of persistence intervals to file.
+**/
+template <typename Filtration_type, typename Coefficient_field>
+class Persistence_interval_common {
+ public:
+  /**
+   * Constructor taking as an input birth and death of the pair.
+  **/
+  Persistence_interval_common(Filtration_type birth, Filtration_type death)
+      : birth_(birth),
+        death_(death),
+        dimension_(std::numeric_limits<unsigned>::max()),
+        arith_element_(std::numeric_limits<Coefficient_field>::max()) {}
+
+  /**
+   * Constructor taking as an input birth, death and dimension of the pair.
+  **/
+  Persistence_interval_common(Filtration_type birth, Filtration_type death, unsigned dim)
+      : birth_(birth), death_(death), dimension_(dim), arith_element_(std::numeric_limits<Coefficient_field>::max()) {}
+
+  /**
+* Constructor taking as an input birth, death, dimension of the pair as well
+* as the number p such that this interval is present over Z_p field.
+**/
+  Persistence_interval_common(Filtration_type birth, Filtration_type death, unsigned dim, Coefficient_field field)
+      : birth_(birth), death_(death), dimension_(dim), arith_element_(field) {}
+
+  /**
+   * Operator to compare two persistence pairs. During the comparision all the
+   * fields: birth, death, dimensiona and arith_element_ are taken into account
+   * and they all have to be equal for two pairs to be equal.
+  **/
+  bool operator==(const Persistence_interval_common& i2) const {
+    return ((this->birth_ == i2.birth_) && (this->death_ == i2.death_) && (this->dimension_ == i2.dimension_) &&
+            (this->arith_element_ == i2.arith_element_));
+  }
+
+  /**
+   * Check if two persistence paris are not equal.
+  **/
+  bool operator!=(const Persistence_interval_common& i2) const { return (!((*this) == i2)); }
+
+  /**
+   * Operator to compare objects of a type Persistence_interval_common.
+   * One intervals is smaller than the other if it has lower persistence.
+   * Note that this operator do not take Arith_element into account when doing comparisions.
+  **/
+  bool operator<(const Persistence_interval_common& i2) const {
+    return fabs(this->death_ - this->birth_) < fabs(i2.death_ - i2.birth_);
+  }
+
+  friend std::ostream& operator<<(std::ostream& out, const Persistence_interval_common& it) {
+    if (it.arith_element_ != std::numeric_limits<Coefficient_field>::max()) {
+      out << it.arith_element_ << "  ";
+    }
+    if (it.dimension_ != std::numeric_limits<unsigned>::max()) {
+      out << it.dimension_ << " ";
+    }
+    out << it.birth_ << " " << it.death_ << " ";
+    return out;
+  }
+
+ private:
+  Filtration_type birth_;
+  Filtration_type death_;
+  unsigned dimension_;
+  Coefficient_field arith_element_;
+};
+
+/**
+ * This function write a vector<Persistence_interval_common> to a stream
+**/
+template <typename Persistence_interval_range>
+void write_persistence_intervals_to_stream(const Persistence_interval_range& intervals,
+                                           std::ostream& out = std::cout) {
+  for (auto interval : intervals) {
+    out << interval << "\n";
+  }
+}
+
+}  // namespace Gudhi
+
+#endif  // WRITING_PERSISTENCE_TO_FILE_H_