Curve Fitting of Type y=ax^b Using C
This article is implementation of pseudocode Curve Fitting of Type y=axb Pseudocode using C programming language.
C Program for Fitting y = axb
#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;
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 + log(x[i]);
sumX2 = sumX2 + log(x[i])*log(x[i]);
sumY = sumY + log(y[i]);
sumXY = sumXY + log(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 */
a = exp(A);
/* Displaying value of a and b */
printf("Values are: a=%0.2f and b = %0.2f",a,b);
getch();
return(0);
}
Curve Fitting y = axb C Program Output
How many data points? 4 x[1]=61 y[1]=350 x[2]=26 y[2]=400 x[3]=7 y[3]=500 x[4]=2.6 y[4]=600 Values are: a=701.99 and b = -0.17
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