CTITLEMINPH  -- COMPUTES MINIMUM PHASE SPECTRUM                         00000010
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CA       AUTHOR                 N. D. CRUMP                             00000020
CA       DESIGNER               N. D. CRUMP                             00000030
CA       LANGUAGE               FORTRAN 77                              00000040
CA       SYSTEM                 IBM & CRAY                              00000041
CA       WRITTEN                1972                                    00000050
C        REVISED                MO-DA-YR                                00000060
C        REVISED                05-20-85 TWH. ADAPT TO RUN ON IBM &     00000061
C                                        CRAY SYSTEMS.                  00000062
C                                                                       00000070
CA                                                                      00000080
CA                                                                      00000090
CA       CALL MINPH (CR, CI, NEXP)                                      00000100
CA             IN/OUT CR     = REAL PART OF FFT                   R8    00000110
CA             IN/OUT CI     = IMAG. PART OF FFT                  R8    00000120
CA             INPUT  NEXP   = LOG BASE 2 OF LENGTH OF FFT        I4    00000130
CA                                                                      00000140
CA                                                                      00000150
CA              THIS ROUTINE ACCEPTS THE FFT OF A TIME FUNCTION         00000160
CA        AND RETURNS THE FFT OF ITS MINIMUM PHASE EQUIVALENT           00000170
CA        (OUTPUT RETURNED IN PLACE).                                   00000180
CA                                                                      00000190
CA                                                                      00000200
C                                                                       00000210
C    SUBROUTINES CALLED: MFORAX                                         00000220
C                        ARSET                                          00000230
C     EJECT                                                             00000240
C                                                                       00000250
      SUBROUTINE MINPH(CR,CI,NEXP)                                      00000260
CAEND                                                                   00000261
      IMPLICIT DOUBLE PRECISION(A-H,O-Z)                                00000263
C                                                                       00000264
      COMMON /SYSTEM/  SYSTEM                                           00000271
      COMMON /SYSTEM/  SYBYPW                                           00000272
      COMMON /SYSTEM/  SYLOCF                                           00000273
C                                                                       00000280
      INTEGER SYSTEM,SYBYPW,SYLOCF                                      00000291
      DIMENSION CR(1),CI(1)                                             00000300
      L = 2**NEXP                                                       00000310
      LWDS=(8/SYBYPW)*L                                                 00000311
      CALL ARSET (CI, LWDS, 0.)                                         00000320
      CALL MFORAX(NEXP,CR,CI,1)                                         00000330
      LH=L/2                                                            00000340
      LP2=L+2                                                           00000350
C                                                                       00000360
          DO                                                        10  00000370
     *    I=2,LH                                                        00000380
          CR(I)=2.*CR(I)                                                00000390
C                                                                       00000400
   10     CR(LP2-I)=0.D0                                                00000410
C                                                                       00000420
      CALL ARSET (CI, LWDS, 0.)                                         00000430
      CALL MFORAX(NEXP,CR,CI,-1)                                        00000440
      RETURN                                                            00000450
      END                                                               00000460