C program - Newton Raphson method

/*newton raphson method*/

#include<stdio.h>

#include<math.h>

void

main()

{

                int count=0;

                float x0,xn,fx,dfx;

                printf("enter the guess value:");

                scanf("%f",&x0);

                /*iteration process*/

label: fx=log(x0)-x0+2;

                   dfx=pow(x0,-1)-1;

                   xn=x0-(fx/dfx);

                   if((fabs(xn-x0))<0.001)

                                   printf("\n the final root is %.4f \n",xn);

                   else

                   {x0=xn;

                   count=count+1;

                   if (count>100)

                   {

                                   printf("the solution does not converge");

                                   printf("enter a different guess value:");

                   }

                   else

                                   goto label;

                   }

}

Result1:

enter the guess value:2

 the final root is 3.1462

Press any key to continue

Result2:

enter the guess value:10

 the final root is 3.1462

Press any key to continue

/*least square fitting of a(x^b)*/

#include<stdio.h>

#include<math.h>

void

main()

{

int n,i;

float a,b,x[20],y[20],x1[20],y1[20],sx=0.0,sxx=0.0,sy=0.0,sxy=0.0,c,m,e=2.71828;

printf("enter the total number of data:");

scanf("%d",&n);

printf("enter the value of x:");

for(i=0;i<n;i++)

{

                scanf("%f",&x[i]);

}

printf("enter the values of y:");

for(i=0;i<n;i++)

{

                scanf("%f",&y[i]);

}

for(i=0;i<n;i++)

{

x1[i]=log(x[i]);

y1[i]=log(y[i]);

                sx=sx+x1[i];

                sxx=sxx+(x1[i]*x1[i]);

                sy=sy+y1[i];

                sxy=sxy+(x1[i]*y1[i]);

}

m=(n*sxy-sx*sy)/(n*sxx-sx*sx);

c=(sxx*sy-sx*sxy)/(n*sxx-sx*sx);

a=pow(e,c);

b=m;

printf("the line of least fit is:\n y=(%f)(x,(%f))\n",a,b);

}

Result:

enter the total number of data:5

enter the value of x:1 2 3 4 5

enter the values of y:20 30 38 43 48

the line of least fit is:

 y=(20.295511)(x,(0.546196))

Press any key to continue