Linear Regression Method Using C++ with Output

This program is implementation of linear regression method as discussed in Linear Regression Method Algorithm and Linear Regression Method Pseudocode using C++.

C++ Program for Linear Regression

``````
#include<iostream>

#define S 50

using namespace std;
int main()
{
int n, i;
float x[S], y[S], sumX=0, sumX2=0, sumY=0, sumXY=0, a, b;

/* Input */
cout<<"How many data points? ";
cin>>n;

cout<<"Enter data:"<< endl;

for(i=1;i<=n;i++)
{
cout<<"x["<< i <<"] = ";
cin>>x[i];
cout<<"y["<< i <<"] = ";
cin>>y[i];
}

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

/* Displaying value of a and b */
cout<<"Calculated value of a is "<< a << "and b is "<< b << endl;
cout<<"Equation of best fit is: y = "<< a <<" + "<< b<<"x";

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

Output

```How many data points? 4
Enter data:
x[1] = 0
y[1] = -1
x[2] = 2
y[2] = 5
x[3] = 5
y[3] = 12
x[4] = 7
y[4] = 20
Calculated value of a is -1.13793and b is 2.89655
Equation of best fit is: y = -1.13793 + 2.89655x
```