# Curve Fitting of Type y=ab^x Using C

This article is implementation of algorithm Curve Fitting of Type y=abx Algorithm and pseudocode Curve Fitting of Type y=abx Pseudocode discussed earlier using C programming language. Output of program is also provided.

## C Program for Fitting y=abx

``````
#include<stdio.h>
#include<conio.h>
#include<math.h>

#define S 50

int main()
{
int n, i;
float x[S], y[S], sumX=0, sumX2=0, sumY=0, sumXY=0, a, b, A, B;
clrscr();

/* Input */
printf("How many data points?\n");
scanf("%d", &n);
for(i=1;i<=n;i++)
{
printf("x[%d]=",i);
scanf("%f", &x[i]);
printf("y[%d]=",i);
scanf("%f", &y[i]);
}

/* Calculating Required Sum */
for(i=1;i<=n;i++)
{
sumX = sumX + x[i];
sumX2 = sumX2 + x[i]*x[i];
sumY = sumY + log(y[i]);
sumXY = sumXY + x[i]*log(y[i]);
}

/* Calculating a and b */
B = (n*sumXY-sumX*sumY)/(n*sumX2-sumX*sumX);
A = (sumY - B*sumX)/n;

/* Transformation of A to a and B to b */
a = exp(A);
b = exp(B);

/* Displaying value of a and b */
printf("Values are: a=%0.2f and b = %0.2f",a,b);

getch();
return(0);
}
``````

## C Program Output for Fitting y=abx

```How many data points?
5
x=0
y=2
x=1
y=7
x=2
y=11
x=3
y=26
x=4
y=50
Values are: a=2.44 and b = 2.17
```