Loops

[GolfinRover]

Using the Newton-Raphson method, find the two roots of the equation 3x^2 + 2x -2=0. (Hint: There is one positive root and one negative root.)

(x+1) = x - (3x^2 +2x -2) / (6x +2) This is the equation given for the Newton-Raphson method.

 Head File 
#include <iostream>
#include <cmath>
using namespace std;
#include "Newton.cpp"
#include "Euler.cpp"
#include "displaymenu.cpp"  
 
 Main Program File
 
#include "head.h"
 
int main(void)    //Note…some code will be removed after buffering test.
{
//Declare all variables here that are needed to call/receive values for Exercises
double guess=1.0, root=0.0;    //variables needed for Exercise 6.a. in case A.
double differs=0.000001, eApprox=0.0;    //variables needed for case B.
char choice = 81;  // 81 is decimal code for capital Q; 113 is lower case q
int enterkey;
do {
    //Your displaymenu() function will replace the next 6 steps 
     cout <<"Call displaymenu and enter an a  ";//desplaymenu()   
        choice = toupper(getchar( ));  enterkey = getchar( );
        cout << choice <<":"<< enterkey << endl;
switch (choice)    // a decision structure to select only one case out of many
{
case 'A':    
    cout<<"Call Newton(given guess), returns and saves root\n ";    // Exercise 6.a.
    root=Newton(guess);
    cout<<"Newton's root is:  "<<root;
break;
case 'B':    
    cout<<"Call Euler(given differs), returns and saves eApprox\n";     // Exercise 3.
    cout<<" differs is set to:  "<<differs<<endl;
    //eApprox = Euler(differs);
    cout<<" eApproximate is:  "<<eApprox<<endl;
break;            
default:    //input data validation intercepted here
if (choice != 'Q')    // a decision structure to skip or enter next {block}
{cout << "\nIncorrect Choice: Enter (A,B, or Q as valid)\n";
}//endif
} //  end switch
 
} while (choice != 'Q');  //end do-while
 
cout << " Fini\n";
 
 
system("pause");
return 0;
} // end main
 
 
 Newton File  My newton does not work  at the moment.
double Newton(double x)   // returns y = f(x)
{
    double root;
int count;
    for (count = 1; count < 10; count++);
    {
 
  cout<<" The x value of Newton is:  "<<x<<endl;
  cout<<"The root: "<<root<<endl;
  root=x-((3(pow((x),2))+2x-2)/(6x+2));
    }//end for
   return root;
 
} //end Newton
 

I still didnt make the Euler file or displaymenu file.

[r035198x]

..
I still didnt make the Euler file or displaymenu file.

Where is your displaymenu function/file?

[JosAH]

My newton does not work at the moment.

double Newton(double x)   // returns y = f(x)
{
    double root;
int count;
    for (count = 1; count < 10; count++);
    {
 
  cout<<" The x value of Newton is:  "<<x<<endl;
  cout<<"The root: "<<root<<endl;
  root=x-((3(pow((x),2))+2x-2)/(6x+2));
    }//end for
   return root;
 
} //end Newton
 

Of course it doesn't work: you assign the same value to your variable 'root'
over and over again. On top of that: 2x doesn't mean 2*x in C or C++; those
languages are a bit stupid, they need an explicit multiplication sign. You have
to fix your notation at several locations.

kind regards,

Jos