gistfile1.f90

      SUBROUTINE SEARCH1(IDATA,IDX,INPUT,IOUT,N)
      IMPLICIT NONE
      INTEGER IDATA,IDX,INPUT,IOUT,I,N,IL,IR,IC
      DIMENSION IDATA(N),IDX(N),INPUT(N),IOUT(N)
      DO 20 I=1,N
         IL=1
         IR=N
 30      IC=(IL+IR)/2
         IF(IDATA(IDX(IC)).EQ.INPUT(I))THEN
            IOUT(I)=IC
         ELSE
            IF(IDATA(IDX(IC)).GT.INPUT(I))THEN
               IR=IC-1
            ELSE
               IL=IC+1
            END IF
            GO TO 30
         END IF
 20   CONTINUE
C
      RETURN
      END
C
      SUBROUTINE SEARCH2(IDATA,IDX,INPUT,IOUT,N)
      IMPLICIT NONE
      INTEGER IDATA,IDX,INPUT,IOUT,ITMP,I,N,IL,IR,IC
      DIMENSION IDATA(N),IDX(N),INPUT(N),ITMP(N),IOUT(N)
      DO 10 I=1,N
         ITMP(I)=IDATA(IDX(I))
 10   CONTINUE
      DO 20 I=1,N
         IL=1
         IR=N
 30      IC=(IL+IR)/2
         IF(ITMP(IC).EQ.INPUT(I))THEN
            IOUT(I)=IC
         ELSE
            IF(ITMP(IC).GT.INPUT(I))THEN
               IR=IC-1
            ELSE
               IL=IC+1
            END IF
            GO TO 30
         END IF
 20   CONTINUE
C
      RETURN
      END
C
      IMPLICIT NONE
      INTEGER IDATA,IDX,INPUT,IOUT1,IOUT2,I,J,NN,N
      INTEGER ISTART,IEND,IRATE,IMAX,NDIFF
      REAL*8 TIME1,TIME2
      PARAMETER(NN=24,N=2**NN)
      DIMENSION IDATA(N),IDX(N),INPUT(N),IOUT1(N),IOUT2(N)
C
      DO 10 I=1,N
         IDATA(I)=1
         DO 20 J=1,NN
            IF(MOD((I-1)/2**(J-1),2).EQ.1)THEN
               IDATA(I)=IDATA(I)+2**(NN-J)
            END IF
 20      CONTINUE
         IDX(I)=IDATA(I)
         INPUT(I)=IDATA(I)
 10   CONTINUE
      CALL SEARCH1(IDATA,IDX,INPUT,IOUT1,N)
      CALL SYSTEM_CLOCK(ISTART,IRATE,IMAX)
      CALL SEARCH1(IDATA,IDX,INPUT,IOUT1,N)
      CALL SYSTEM_CLOCK(IEND,IRATE,IMAX)
      TIME1=DBLE(IEND-ISTART)/DBLE(IRATE)
      CALL SEARCH2(IDATA,IDX,INPUT,IOUT2,N)
      CALL SYSTEM_CLOCK(ISTART,IRATE,IMAX)
      CALL SEARCH2(IDATA,IDX,INPUT,IOUT2,N)
      CALL SYSTEM_CLOCK(IEND,IRATE,IMAX)
      TIME2=DBLE(IEND-ISTART)/DBLE(IRATE)
      NDIFF=0
      DO 30 I=1,N
         IF(IOUT1(I).NE.IOUT2(I))THEN
            NDIFF=NDIFF+1
         END IF
 30   CONTINUE
      WRITE(*,*)TIME1,TIME2,NDIFF
      END