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Annotation of rpl/lapack/lapack/dzsum1.f, revision 1.7

1.1       bertrand    1:       DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
                      2: *
                      3: *  -- LAPACK auxiliary routine (version 3.2) --
                      4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                      5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                      6: *     November 2006
                      7: *
                      8: *     .. Scalar Arguments ..
                      9:       INTEGER            INCX, N
                     10: *     ..
                     11: *     .. Array Arguments ..
                     12:       COMPLEX*16         CX( * )
                     13: *     ..
                     14: *
                     15: *  Purpose
                     16: *  =======
                     17: *
                     18: *  DZSUM1 takes the sum of the absolute values of a complex
                     19: *  vector and returns a double precision result.
                     20: *
                     21: *  Based on DZASUM from the Level 1 BLAS.
                     22: *  The change is to use the 'genuine' absolute value.
                     23: *
                     24: *  Contributed by Nick Higham for use with ZLACON.
                     25: *
                     26: *  Arguments
                     27: *  =========
                     28: *
                     29: *  N       (input) INTEGER
                     30: *          The number of elements in the vector CX.
                     31: *
                     32: *  CX      (input) COMPLEX*16 array, dimension (N)
                     33: *          The vector whose elements will be summed.
                     34: *
                     35: *  INCX    (input) INTEGER
                     36: *          The spacing between successive values of CX.  INCX > 0.
                     37: *
                     38: *  =====================================================================
                     39: *
                     40: *     .. Local Scalars ..
                     41:       INTEGER            I, NINCX
                     42:       DOUBLE PRECISION   STEMP
                     43: *     ..
                     44: *     .. Intrinsic Functions ..
                     45:       INTRINSIC          ABS
                     46: *     ..
                     47: *     .. Executable Statements ..
                     48: *
                     49:       DZSUM1 = 0.0D0
                     50:       STEMP = 0.0D0
                     51:       IF( N.LE.0 )
                     52:      $   RETURN
                     53:       IF( INCX.EQ.1 )
                     54:      $   GO TO 20
                     55: *
                     56: *     CODE FOR INCREMENT NOT EQUAL TO 1
                     57: *
                     58:       NINCX = N*INCX
                     59:       DO 10 I = 1, NINCX, INCX
                     60: *
                     61: *        NEXT LINE MODIFIED.
                     62: *
                     63:          STEMP = STEMP + ABS( CX( I ) )
                     64:    10 CONTINUE
                     65:       DZSUM1 = STEMP
                     66:       RETURN
                     67: *
                     68: *     CODE FOR INCREMENT EQUAL TO 1
                     69: *
                     70:    20 CONTINUE
                     71:       DO 30 I = 1, N
                     72: *
                     73: *        NEXT LINE MODIFIED.
                     74: *
                     75:          STEMP = STEMP + ABS( CX( I ) )
                     76:    30 CONTINUE
                     77:       DZSUM1 = STEMP
                     78:       RETURN
                     79: *
                     80: *     End of DZSUM1
                     81: *
                     82:       END