FORTRAN code: LEAST SQUARE METHOD

 Source code:

c PROGRAM FOR FITTING GIVEN DATA TO A STRAIGHT LINE USING LEAST SQUARE METHOD

DIMENSION X(100),Y(100)

REAL X,Y

WRITE(*,*)'HOW MANY NUMBERS ARE THERE'

READ(*,*)N

WRITE(*,*)'ENTER DATA POINTS NOW'

READ(*,*)(X(I),Y(I),I=1,N)

SUMX=0.0

SUMY=0.0

SUMXX=0.0

SUMXY=0.0

DO 10 I=1,N

SUMX=SUMX+X(I)

SUMY=SUMY+Y(I)

SUMXX=SUMXX+X(I)**2

SUMXY=SUMXY+X(I)*Y(I)

10 CONTINUE

DENOM=FLOAT(N)*SUMXX-SUMX**2

A=(SUMY*SUMXX-SUMX*SUMXY)/DENOM

B=(FLOAT(N)*SUMXY-SUMX*SUMY)/DENOM

WRITE(*,*)'INTERCEPT OF BEST FITTING LINE ON Y-AXIS IS',A

WRITE(*,*)'SLOPE OF BEST FIT LINE IS',B

WRITE(*,*)'BEST FIT DATA POINTS ARE'

DO 20 I=1,N

Y(I)=A+B*X(I)

WRITE(*,*)X(I),Y(I)

20 CONTINUE

STOP

END