Please Help Me With Some Errors

Question

mzdiva041986 0 Newbie Poster

16 Years Ago

I have some errors that I can't seem to understand, could someone help me clear up this problem?

#include <cmath>
#include <iostream> 
using namespace std;

double F ( double X )
{  
	
  return pow ( X, 4) - 9*pow ( X, 3 ) - 2*pow (X, 2) + 120*X - 130;
}

double DF (double X)
{
	return 4*pow (X, 3) - 27*pow (X, 2) - 4*X + 120;
}

double DDF (double X)
{
	return 12*pow (X, 2) - 54*X -4;
}

int main()
{
  int TALLEY;
  double X, XL, XR, XS, Y, YL, YR;
  double XB, XND, STEPSIZE;
  double XO, XN, FX, DFX, DDFX;
  double INT_ACC, ROOT_ACC, TOO_BIG, TOO_SMALL;

  TALLEY = 0;
  
  XL = 0.0;
  XR = 0.0;
  XS = 0.0;

  X = 0.0;
  Y = 0.0;
  YL = 0.0;
  YR = 0.0;

  XB = 0.0;
  XND = 0.0;
  STEPSIZE = 0.0;

  XO = 0.0;
  XN = 0.0;
  FX = 0.0;
  DFX = 0.0;
  DDFX = 0.0;

  INT_ACC = 0.0;
  ROOT_ACC = 0.0;
  TOO_BIG = 0.0;
  TOO_SMALL = 0.0;

  cout<<"What is the left-most interval endpoint? ";
  cin>> XB;

  cout<<"What is the right-most interval endpoint? ";
  cin>> XND;

  cout<<"What is the desired step-size for function evaluation? ";
  cin>> STEPSIZE;

  cout<<"How close can the approximate root be to the true root to invoke root-finding? ";
  cin>> INT_ACC;

  cout<<"What is the size limit on the 2nd derivative? ";
  cin>> TOO_BIG;

  cout<<"How close can the 1st derivative get to zero? ";
  cin>> TOO_SMALL;

  cout<<"What is the desired accuracy for root-finding? ";
  cin>> ROOT_ACC;


  XL = XB;

  while ( true ) {
    YL = F ( XL );
    XR = XL + STEPSIZE;
    YR = F ( XR );

    if ( YL * YR > 0 ) {
      if ( XR >= XND ) goto end;

      XL = XR;
      YL = YR;
    }

    if ( YL * YR == 0 ) {
      if ( YL == 0.0 ) {
        cout<<"This is a root. "<< XL<<endl;

        if ( XR >= XND ) goto end;

        XL = XR;
      }
      else {
        cout<<"This is a root. "<< XR<<endl;

        if ( XR >= XND ) goto end;

        XL = XR + STEPSIZE;
      }
    }

    if ( YL * YR < 0 ) {
      XS = XR;

      while ( true ) {
        X = ( XL + XR ) / 2.0;
        Y = F ( X );

        if ( YL * Y > 0 ) {
          XL = X;
          YL = Y;
        }

        if ( YL * Y == 0 ) {
          cout<<"This is a root. "<< X<<endl;

          XR = X;
          YR = Y;
        }

        if ( YL * Y < 0 ) {
          XR = X;
          YR = Y;
        }

        if ( fabs(XR - XL) < INT_ACC) {
         cout<<"This interval contains a root at "<< XL <<','<< XR<<endl;
	
           XO = (XL + XR)/2.0;

           TALLEY = 1;

           while ( true ) {
	FX = F(XO);
	DFX = DF(XO);
	DDFX= DDF(XO);

            if (fabs(DDFX)>= TOO_BIG) {

	cout<<"Condition 1 FAILS: 2nd derivative too large. ";

           }
}

	if (fabs(DFX) <= TOO_SMALL) {

	cout<<"Condition 2 FAILS: 1st derivative too close to zero. ";

	}
}

	if (TALLEY > 15) {
	cout<<"Slow convergence. Possible infinite loop.";

	}
 }

	XN = XO - (FX/DFX);

	if (fabs(XN-XO) < ROOT_ACC) {
	cout<<"The root is: "<<XN<<endl;
	}

	       else

	XO = XN;
	TALLEY = TALLEY + 1;

	}
  }


	XL = XS;

          if ( XL >= XND ) goto end;

          break;
        }
      }
    }
  }
}


end:
  return 0;
}

Here are the errors that are shown:

F:\C ++ Numerical Methods\Newton_Raphson.cpp(183) : error C2043: illegal break
F:\C ++ Numerical Methods\Newton_Raphson.cpp(184) : warning C4508: 'main' : function should return a value; 'void' return type assumed
F:\C ++ Numerical Methods\Newton_Raphson.cpp(185) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(185) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(185) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(186) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(186) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(187) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(187) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(188) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(188) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(192) : error C2143: syntax error : missing ';' before 'return'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(193) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(193) : error C2143: syntax error : missing ';' before '}'
F:\C ++ Numerical Methods\Newton_Raphson.cpp(193) : error C2143: syntax error : missing ';' before '}'
Error executing cl.exe.

Newton_Raphson.obj - 14 error(s), 1 warning(s)

c++

3 Contributors
2 Replies
117 Views
20 Hours Discussion Span
Latest Post 16 Years Ago Latest Post by WaltP

All 2 Replies

Traicey 10 Posting Whiz in Training

16 Years Ago

Just to make it readable *wink*

#include <cmath>
#include <iostream> 
using namespace std;

double F ( double X )
{
       return pow ( X, 4) - 9*pow ( X, 3 ) - 2*pow (X, 2) + 120*X - 130;
}

double DF (double X)
{
       return 4*pow (X, 3) - 27*pow (X, 2) - 4*X + 120;
}

double DDF (double X)
{
       return 12*pow (X, 2) - 54*X -4;
}

int main()
{
    int TALLEY;
    double X, XL, XR, XS, Y, YL, YR;
    double XB, XND, STEPSIZE;
    double XO, XN, FX, DFX, DDFX;
    double INT_ACC, ROOT_ACC, TOO_BIG, TOO_SMALL;

    TALLEY = 0;

    XL = 0.0;
    XR = 0.0;
    XS = 0.0;

    X = 0.0;
    Y = 0.0;
    YL = 0.0;
    YR = 0.0;

    XB = 0.0;
    XND = 0.0;
    STEPSIZE = 0.0;

    XO = 0.0;
    XN = 0.0;
    FX = 0.0;
    DFX = 0.0;
    DDFX = 0.0;

    INT_ACC = 0.0;
    ROOT_ACC = 0.0;
    TOO_BIG = 0.0;
    TOO_SMALL = 0.0;

    cout<<"What is the left-most interval endpoint? ";
    cin>> XB;

    cout<<"What is the right-most interval endpoint? ";
    cin>> XND;

    cout<<"What is the desired step-size for function evaluation? ";
    cin>> STEPSIZE;

    cout<<"How close can the approximate root be to the true root to invoke root-finding? ";
    cin>> INT_ACC;

    cout<<"What is the size limit on the 2nd derivative? ";
    cin>> TOO_BIG;

    cout<<"How close can the 1st derivative get to zero? ";
    cin>> TOO_SMALL;

    cout<<"What is the desired accuracy for root-finding? ";
    cin>> ROOT_ACC;


    XL = XB;

    while ( true ) 
    {
          YL = F ( XL );
          XR = XL + STEPSIZE;
          YR = F ( XR );

          if ( YL * YR > 0 ) 
         {
             if ( XR >= XND ) goto end;

             XL = XR;
             YL = YR;
         }

    if ( YL * YR == 0 ) 
    {
       if ( YL == 0.0 ) 
       {
          cout<<"This is a root. "<< XL<<endl;

          if ( XR >= XND ) goto end;
             XL = XR;
       }
    else 
    {
           cout<<"This is a root. "<< XR<<endl;

           if ( XR >= XND ) goto end;

           XL = XR + STEPSIZE;
       }
    }//end if

    if ( YL * YR < 0 ) 
    {
       XS = XR;
       while ( true ) 
       {
             X = ( XL + XR ) / 2.0;
             Y = F ( X );

             if ( YL * Y > 0 ) 
             {
                XL = X;
                YL = Y;
             }

             if ( YL * Y == 0 ) 
             {
                cout<<"This is a root. "<< X<<endl;

                XR = X;
                YR = Y;
             }

             if ( YL * Y < 0 ) 
             {
                XR = X;
                YR = Y;
             }

             if ( fabs(XR - XL) < INT_ACC) 
             {
                cout<<"This interval contains a root at "<< XL <<','<< XR<<endl;

                XO = (XL + XR)/2.0;

                TALLEY = 1;

                while ( true ) 
                {
                      FX = F(XO);
                      DFX = DF(XO);
                      DDFX= DDF(XO);

                      if (fabs(DDFX)>= TOO_BIG) 
                      {
                         cout<<"Condition 1 FAILS: 2nd derivative too large. ";
                      }
                      break;
                }// end of while

                if (fabs(DFX) <= TOO_SMALL) 
                {
                   cout<<"Condition 2 FAILS: 1st derivative too close to zero. ";

                }
            }//end if

         if (TALLEY > 15) 
         {
            cout<<"Slow convergence. Possible infinite loop.";
         }
     }//end while

         XN = XO - (FX/DFX);

         if (fabs(XN-XO) < ROOT_ACC) 
         {
            cout<<"The root is: "<<XN<<endl;
         }
         else
         {
             XO = XN;
             TALLEY = TALLEY + 1;
             break;

          }


             XL = XS;

             if ( XL >= XND ) goto end;
             break;


}//whats this for
}//whats this for
}//whats this for
}//whats this for
}//whats this for


end:
return 0;
}//end main method

Reply to this topic

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.

WaltP 2,905 Posting Sage w/ dash of thyme Team Colleague · Answer 1 · 2008-03-27T00:09:08+00:00

Yes, as Traicey implied, learn to format your code. Most of the errors you would have found without asking. F:\C ++ Numerical Methods\Newton_Raphson.cpp(183) : error C2043: illegal break -- a break must be within a loop or switch F:\C ++ Numerical Methods\Newton_Raphson.cpp(184) : warning C4508: 'main' : function should return a value; 'void' return type assumed main() is an int function -- see this -- and must return a value.

Please Help Me With Some Errors

Recommended Answers Collapse Answers

All 2 Replies

Recommended Answers