polyop.hh

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#ifndef __RVL_TOOLS_POLYOP_H_
#define __RVL_TOOLS_POLYOP_H_

#include "functions.hh"
#include "op.hh"

namespace RVL {

  template<class Scalar>
  class PolynomialOperator : public OperatorWithInvertibleDeriv<Scalar> {

  protected:
    Space<Scalar> & spc;
    std::valarray<Scalar> coef;

    virtual void apply(const Vector<Scalar> & x, 
               Vector<Scalar> & y) const {
      Vector<Scalar> temp(x);
      ElementwiseMultiply<Scalar> dotstar;
      int size = coef.size();
      if( size > 0) {
    RVLAssignConst<Scalar> constantterm(coef[0]);
    y.eval(constantterm);
      }
      if( size > 1 )
    y.linComb(coef[1], temp);
      for( int i = 2; i < size; i++) {
    temp.eval(dotstar, temp, x);
    y.linComb(coef[i], temp);
      }
    }
  
    virtual void applyDeriv(const Vector<Scalar> & x, 
                const Vector<Scalar> & dx,
                Vector<Scalar> & dy) const {
      Vector<Scalar> temp(x);
      ElementwiseMultiply<Scalar> dotstar;
      int size = coef.size();
      if( size > 1) {
    RVLAssignConst<Scalar> constantterm(coef[1]);
    dy.eval(constantterm);
      } else {
    dy.zero();
      }  
      if( size > 2 )
    dy.linComb(coef[2]*Scalar(2), temp);
      for( int i = 3; i < size; i++) {
    temp.eval(dotstar, temp, x);
    dy.linComb(coef[i]*Scalar(i), temp);
      } 
      // dy has DF(x), so we need to do the multiply now.
      dy.eval(dotstar, dy,dx);
    }
  
    virtual void applyAdjDeriv(const Vector<Scalar> & x, 
                   const Vector<Scalar> & dy,
                   Vector<Scalar> & dx) const {
      applyDeriv(x,dy,dx);
    }

    void applyInverseDeriv(const Vector<Scalar> & x,
               const Vector<Scalar> & dy,
               Vector<Scalar> & dx) const {
      Vector<Scalar> temp(x);
      ElementwiseMultiply<Scalar> dotstar;
      int size = coef.size();
      if( size > 1) {
    RVLAssignConst<Scalar> constantterm(coef[1]);
    dx.eval(constantterm);
      } else {
    dx.zero();
      }  
      if( size > 2 )
    dx.linComb(coef[2]*Scalar(2), temp);
      for( int i = 3; i < size; i++) {
    temp.eval(dotstar, temp, x);
    dx.linComb(coef[i]*Scalar(i), temp);
      } 
      // dy has DF(x), so we need to do the division now.
      ElementwiseDivision<Scalar> dotslash;
      dx.eval(dotslash, dy, dx);
    }

    void applyAdjInverseDeriv(const Vector<Scalar> & x,
                  const Vector<Scalar> & dx,
                  Vector<Scalar> & dy) const {
      applyInverseDeriv(x,dx,dy);
    }


    virtual Operator<Scalar> * clone() const { return new PolynomialOperator(*this); }

  public:
  
    PolynomialOperator(const std::valarray<Scalar> & _coef, Space<Scalar> & _spc)
      : spc(_spc), coef(_coef) {}
    PolynomialOperator(const PolynomialOperator<Scalar> & s): spc(s.spc), coef(s.coef) {}
    ~PolynomialOperator() {}
  
    virtual const Space<Scalar> & getDomain() const { return spc; }
    virtual const Space<Scalar> & getRange() const { return spc; }

    virtual void write(RVLException & e) const { 
      e << "PolynomialOperator with coefficients";
      for(int i = 0; i < coef.size(); i++) {
    e << "c[" << i << "] = " << coef[i] << '\n';
      }
    }

    virtual ostream & write(ostream & str) const { 
      str << "PolynomialOperator with coefficients";
      for(int i = 0; i < coef.size(); i++) {
    str << "c[" << i << "] = " << coef[i] << '\n';
      }
    }

  
  };


}

#endif

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