! GAUSS-QUADRATURE METHOD
DIMENSION W(10),Z(10)
WRITE(*,*)'GIVE THE LIMITS OF INTEGRATION'
READ(*,*)TL,TU
WRITE(*,*)'THE NUMBER POINTS USED FOR CALCULATION'
READ(*,*)N
P=(TU-TL)/2
Q=(TU+TL)/2
IF(N.EQ.2)THEN
OPEN(2,FILE='GQUAD2.DAT',STATUS='OLD')
DO I=1,N
READ(2,10)W(I),Z(I)
10 FORMAT(5X,F7.5,5X,F8.5)
WRITE(*,*)W(I),Z(I)
END DO
ELSE
IF(N.EQ.3)THEN
OPEN(3,FILE='GQUAD3.DAT',STATUS='OLD')
DO I=1,N
READ(3,10)W(I),Z(I)
WRITE(*,*)W(I),Z(I)
END DO
ELSE
IF(N.EQ.4)THEN
OPEN(4,FILE='GQUAD4.DAT',STATUS='OLD')
DO I=1,N
READ(4,10)W(I),Z(I)
WRITE(*,*)W(I),Z(I)
END DO
ELSE
IF(N.EQ.5)THEN
OPEN(5,FILE='GQUAD5.DAT',STATUS='OLD')
DO I=1,N
READ(5,10)W(I),Z(I)
WRITE(*,*)W(I),Z(I)
END DO
ELSE
IF(N.EQ.6)THEN
OPEN(6,FILE='GQUAD6.DAT',STATUS='OLD')
DO I=1,N
READ(6,10)W(I),Z(I)
WRITE(*,*)W(I),Z(I)
END DO
ELSE
END IF
END IF
END IF
END IF
END IF
SUM=0
DO I=1,N
SUM=SUM+W(I)*F(P*Z(I)+Q)
WRITE(*,*)SUM
END DO
VALUE=(TU-TL)*SUM/2
WRITE(*,*)TU,TL,VALUE
STOP
END
FUNCTION F(X)
F=X*EXP(2*X)
RETURN
END
