C program for least square fitting of a straight line

/*least square fitting of a straight line */

#include<stdio.h>

#include<math.h>

void

main()

{

int n,i;

float a,b,x[20],y[20],sx=0.0,sxx=0.0,sy=0.0,sxy=0.0;

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++)

{

                sx=sx+x[i];

                sxx=sxx+(x[i]*x[i]);

                sy=sy+y[i];

                sxy=sxy+(x[i]*y[i]);

}

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

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

printf("the line of least fit is:\n y=%fx+%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:2.03 4.26 6.59 8.12 10.28

the line of least fit is:

 y=2.036000x+0.148000

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