CTITLEARCSM  -- COMPUTE MAGNITUDE OF A COMPLEX ARRAY                    00010000
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CA    AUTHOR         STU NELAN                                          00020000
CA    DESIGNER       STU NELAN                                          00030000
CA    LANGUAGE       FORTRAN                                            00040000
CA    SYSTEM         IBM AND CRAY                                       00050000
CA    WRITTEN        03-25-86                                           00060000
C     REVISED        07-11-86 ESN. FOR USE ON THE IBM.                  00070000
C     REVISED        07-21-88 FAC. PREVENT DIVIDE BY ZERO DURING        00071000
C                                  NORMALIZATION.                       00072000
CA                                                                      00080000
CA                                                                      00090000
CA    CALL ARCSM (Z, W, A, N)                                           00100000
CA          INPUT   Z = COMPLEX ARRAY                               C4  00110000
CA          OUTPUT  W = COMPLEX ARRAY                               C4  00120000
CA          OUTPUT  A = REAL ARRAY FOR MAGNITUDE                    R4  00130000
CA          INPUT   N = NUMBER OF ELEMENTS IN EACH ARRAY Z, W,      I4  00140000
CA                      AND A                                           00150000
CA                                                                      00160000
CA                                                                      00170000
CA       ARCSM COMPUTES THE MAGNITUDE SPECTRUM OF THE COMPLEX ARRAY Z   00180000
CA       AND STORES THE RESULT IN THE REAL ARRAY A. ARCSM ALSO DIVIDES  00190000
CA       THE COMPLEX ARRAY Z BY THE RESULTING AMPLITUDE SPECTRUM AND    00200000
CA       STORES THE RESULT IN THE COMPLEX ARRAY W.                      00210000
CA       IE. IF Z(J) = (X+IY) THEN A(J) = SQRT(X**2+Y**2) AND           00220000
CA       W(J) = (X/A(J)+IY/A(J))                                        00230000
CA       Z AND W MAY BE THE SAME ARRAY.                                 00240000
CA       THIS ROUTINE IS MAINLY USED TO CALCULATE THE AMPLITUDE         00250000
CA       SPECTRUM.                                                      00260000
CAEND                                                                   00270000
      SUBROUTINE ARCSM (Z, W, A, N)                                     00280000
C                                                                       00290000
      REAL    A(N)                                                      00300000
      REAL    W(N)                                                      00310000
      REAL    Z(N)                                                      00320000
C                                                                       00330000
          DO 10 I = 1, N                                                00340000
   10     A(I) = SQRT ( Z(2*I-1)*Z(2*I-1) + Z(2*I)*Z(2*I) )             00350000
C                                                                       00360000
          DO 20 I = 1, N                                                00370000
   20       IF( A(I) .NE. 0.0 ) W(2*I-1) = Z(2*I-1) / A(I)              00380000
C                                                                       00390000
          DO 30 I = 1, N                                                00400000
   30       IF( A(I) .NE. 0.0 ) W(2*I) = Z(2*I) / A(I)                  00410000
C                                                                       00420000
      RETURN                                                            00430000
C                                                                       00440000
      END                                                               00450000