symbolic_functions.cc

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#include "symbolic_functions.h"
 
#include <limits>
#include <math.h>
#include <sstream>
#include <string>
 
namespace cyclus {
namespace toolkit {
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
double LinearFunction::value(double x) {
  return slope_ * x + intercept_;
}
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
std::string LinearFunction::Print() {
  std::stringstream ss("");
  ss << "y = " << slope_ << " * x + " << intercept_;
  return ss.str();
}
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
double ExponentialFunction::value(double x) {
  return constant_ * exp(exponent_ * x) + intercept_;
}
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
std::string ExponentialFunction::Print() {
  std::stringstream ss("");
  ss << "y = " << constant_
     << " * exp(" << exponent_ << " * x) + " << intercept_;
  return ss.str();
}
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
double PiecewiseFunction::value(double x) {
  double ret;
  if (functions_.empty() || (x < functions_.front().xoffset)) {
    ret = 0.0;
  } else {
    std::list<PiecewiseFunctionInfo>::iterator f = functions_.begin();
    while (f != functions_.end() && (x >= f->xoffset)) {
      ++f;  // exceeds search by 1
    }
    --f;  // go back to the correct one
    ret = f->function->value(x - f->xoffset) + f->yoffset;
  }
  return ret;
}
 
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
std::string PiecewiseFunction::Print() {
  std::stringstream ss("");
  ss << "Piecewise Function comprised of: ";
  std::list<PiecewiseFunctionInfo>::iterator f;
  for (f = functions_.begin(); f != functions_.end(); f++) {
    ss << " * " << f->function->Print()
       << " starting at coordinate (" << f->xoffset << ","
       << f->yoffset << ")";
  }
  return ss.str();
}
 
}  // namespace toolkit
}  // namespace cyclus