Write A Program To Fit A Straight Line Of The Form y=ax+b


Source Code:

#include<stdio.h>
#include<conio.h>
void main()
{
 //declaring variables
 float x[100],y[100],xy[100],xx[100],a,b;
 float sx=0,sy=0,sxy=0,sxx=0,a1,b1,c1,a2,b2,c2;

 int n,i;
 clrscr();
 printf("This is a program to fit a straight line of the form y=ax+b\n");
 printf("enter the no of observation:");
 scanf("%d",&n);
 //scanning of points
 for(i=0;i<n;i++)
 {
  printf("enter point no %d:",i+1);
  scanf("%g%g",&x[i],&y[i]);
  xy[i]=x[i]*y[i];
  xx[i]=x[i]*x[i];
  sx=sx+x[i];
  sy=sy+y[i];
  sxy=sxy+xy[i];
  sxx=sxx+xx[i];
 }
 printf("the computational table is\n");
 printf("\nx\ty\txy\tx^2\n");
 printf("\n-----\t-----\t-----\t-----\n");
 for(i=0;i<n;i++)
 {
  printf("\n%g\t%g\t%g\t%g\n",x[i],y[i],xy[i],xx[i]);
 }
 printf("\n-----\t-----\t-----\t-----\n");
 printf("\n%g\t%g\t%g\t%g\n",sx,sy,sxy,sxx);
 printf("%g=a.%g+b.%d\n",sy,sx,n);
 printf("%g=a.%g+b.%g\n",sxy,sxx,sx);
 a1=sx;
 b1=n;
 c1=-sy;
 a2=sxx;
 b2=sx;
 c2=-sxy;
 //checking for validation
 if((a1*b2-a2*b1)==0)
 {
  printf("the given points doesnot form a straight line\n:");
 }
 else
 {
  a=(b1*c2-b2*c1)/(a1*b2-a2*b1);
  b=(a2*c1-a1*c2)/(a1*b2-a2*b1);
 }
 //the straight line is
 printf("\n the straight line is y=%gx+%g",a,b);
 getch();
}

}