C INTGL4.F OF N.TAJIMA'S FORTRAN BENCH-MARK TESTS (VER.2)
C CALCULATES A FOUR-DIMENSINAL INTRGRAL.
C HISTORY: 98/6/26
      PROGRAM INTGL4
      IMPLICIT REAL*8 (A-H,O-Z)
      A=0.1D0
      CALL INTG4A(A)
      END
C
      SUBROUTINE INTG4A(A)
      IMPLICIT REAL*8 (A-H,O-Z)
      PARAMETER(N=200,HALF=0.5D0)
      D=1/DBLE(N)
      DH=D*HALF
      F=A**2
      S=0
      DO 40 I1=1,N
        X1=I1*D-DH
        X1H=X1*HALF
        DO 30 I2=1,N
          X2=I2*D-DH
          DX2=(X2-X1)**2
          T=0
          DO 20 J1=1,N
            Y1=J1*D-DH
            X2Y1=X2*Y1
            DO 10 J2=1,N
              Y2=J2*D-DH
              T=T+(X2Y1+X1H*Y2)/(DX2+(Y2-Y1)**2+F)
   10       CONTINUE
   20     CONTINUE
          S=S+T
   30   CONTINUE
   40 CONTINUE
      S=S*D**4
      WRITE(6,900) N,A,S
  900 FORMAT(' #PTS=',I8,'**4  A=',F7.4,'  S=',F18.9)
      END