spline.cc

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/*
 * Copyright 2009-2020 The VOTCA Development Team (http://www.votca.org)
 *
 * 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.
 *
 */
 
// Local VOTCA includes
#include "votca/tools/spline.h"
 
namespace votca {
namespace tools {
 
using namespace std;
 
Index Spline::GenerateGrid(double min, double max, double h) {
  Index vec_size = (Index)((max - min) / h + 1.00000001);
  r_.resize(vec_size);
  int i;
 
  double r_init;
 
  for (r_init = min, i = 0; i < vec_size - 1; r_init += h) {
    r_[i++] = r_init;
  }
  r_[i] = max;
  return r_.size();
}
 
Eigen::VectorXd Spline::Calculate(const Eigen::VectorXd &x) {
  Eigen::VectorXd y(x.size());
  for (Index i = 0; i < x.size(); ++i) {
    y(i) = Calculate(x(i));
  }
  return y;
}
 
Eigen::VectorXd Spline::CalculateDerivative(const Eigen::VectorXd &x) {
  Eigen::VectorXd y(x.size());
  for (Index i = 0; i < x.size(); ++i) {
    y(i) = CalculateDerivative(x(i));
  }
  return y;
}
 
void Spline::Print(std::ostream &out, double interval) {
  for (double x = r_[0]; x < r_[r_.size() - 1]; x += interval) {
    out << x << " " << Calculate(x) << "\n";
  }
}
 
Index Spline::getInterval(double r) {
  if (r < r_[0]) {
    return 0;
  }
  if (r > r_[r_.size() - 2]) {
    return r_.size() - 2;
  }
  Index i;
  for (i = 0; i < r_.size(); ++i) {
    if (r_[i] > r) {
      break;
    }
  }
  return i - 1;
}
 
double Spline::getGridPoint(int i) {
  if (i >= r_.size()) {
    return 0;
  }
  return r_[i];
}
 
}  // namespace tools
}  // namespace votca