CTITLEARPOW  -- COMPUTE MAGNITUDE SQUARED OF COMPLEX ARRAY              00010000
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CA    AUTHOR         FRANCIS COLLINS                                    00020000
CA    DESIGNER       FRANCIS COLLINS                                    00030001
CA    LANGUAGE       FORTRAN                                            00040002
CA    SYSTEM         IBM AND CRAY                                       00050002
CA    WRITTEN        08-25-81                                           00060000
C     REVISED        07-11-86 ESN. FOR USE ON THE IBM.                  00070002
CA                                                                      00080000
CA                                                                      00090000
CA    CALL ARPOW (Z, P, N)                                              00100000
CA          INPUT   Z = COMPLEX ARRAY                               C4  00110000
CA          OUTPUT  P = REAL ARRAY                                  R4  00120000
CA          INPUT   N = NUMBER OF ELEMENTS IN EACH ARRAY A AND P    I4  00130000
CA                                                                      00140000
CA                                                                      00150000
CA       ARPOW COMPUTES THE MAGNITUDE SQUARED OF THE COMPLEX ARRAY Z    00160000
CA       AND STORES THE RESULT IN THE REAL ARRAY P.                     00170000
CA       IE. IF Z(J) = (X+IY) THEN P(J) = X**2 + Y**2                   00180000
CA       Z AND P MAY BE THE SAME ARRAY.                                 00190000
CA                                                                      00200000
CA       ARRAY P IS NORMALLY USED AS THE POWER SPECTRUM.                00210000
CAEND                                                                   00220000
      SUBROUTINE ARPOW (Z, P, N)                                        00230000
C                                                                       00240000
      REAL        Z (2*N)                                               00250000
      REAL        P (  N)                                               00260000
C                                                                       00270000
      J = 1                                                             00280000
          DO 10  I = 1, N                                               00290000
          P(I) = Z(J)*Z(J) + Z(J+1)*Z(J+1)                              00300000
          J    = J + 2                                                  00310000
   10     CONTINUE                                                      00320000
C                                                                       00330000
      RETURN                                                            00340000
      END                                                               00350000