C program for least square fitting of aexp(bx)

/*least square fitting of aexp(bx) */

#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]=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=%fe^(%fx)\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:70 259 920 3340 12000

the line of least fit is:

 y=19.563120e^(1.284523x)

Press any key to continue