sasum.f

      REAL FUNCTION SASUM (N, SX, INCX)
C***BEGIN PROLOGUE  SASUM
C***PURPOSE  Compute the sum of the magnitudes of the elements of a
C            vector.
C***LIBRARY   SLATEC (BLAS)
C***CATEGORY  D1A3A
C***TYPE      SINGLE PRECISION (SASUM-S, DASUM-D, SCASUM-C)
C***KEYWORDS  BLAS, LINEAR ALGEBRA, SUM OF MAGNITUDES OF A VECTOR
C***AUTHOR  Lawson, C. L., (JPL)
C           Hanson, R. J., (SNLA)
C           Kincaid, D. R., (U. of Texas)
C           Krogh, F. T., (JPL)
C***DESCRIPTION
C
C                B L A S  Subprogram
C    Description of Parameters
C
C     --Input--
C        N  number of elements in input vector(S)
C       SX  single precision vector with N elements
C     INCX  storage spacing between elements of SX
C
C     --Output--
C    SASUM  single precision result (zero if N .LE. 0)
C
C     Returns sum of magnitudes of single precision SX.
C     SASUM = sum from 0 to N-1 of ABS(SX(IX+I*INCX)),
C     where IX = 1 if INCX .GE. 0, else IX = 1+(1-N)*INCX.
C
C***REFERENCES  C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
C                 Krogh, Basic linear algebra subprograms for Fortran
C                 usage, Algorithm No. 539, Transactions on Mathematical
C                 Software 5, 3 (September 1979), pp. 308-323.
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   791001  DATE WRITTEN
C   890831  Modified array declarations.  (WRB)
C   890831  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900821  Modified to correct problem with a negative increment.
C           (WRB)
C   920501  Reformatted the REFERENCES section.  (WRB)
C***END PROLOGUE  SASUM