*> \brief \b SASUM * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * REAL FUNCTION SASUM(N,SX,INCX) * * .. Scalar Arguments .. * INTEGER INCX,N * .. * .. Array Arguments .. * REAL SX(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> SASUM takes the sum of the absolute values. *> uses unrolled loops for increment equal to one. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in] SX *> \verbatim *> SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of SX *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup single_blas_level1 * *> \par Further Details: * ===================== *> *> \verbatim *> *> jack dongarra, linpack, 3/11/78. *> modified 3/93 to return if incx .le. 0. *> modified 12/3/93, array(1) declarations changed to array(*) *> \endverbatim *> * ===================================================================== REAL FUNCTION SASUM(N,SX,INCX) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX,N * .. * .. Array Arguments .. REAL SX(*) * .. * * ===================================================================== * * .. Local Scalars .. REAL STEMP INTEGER I,M,MP1,NINCX * .. * .. Intrinsic Functions .. INTRINSIC ABS,MOD * .. SASUM = 0.0e0 STEMP = 0.0e0 IF (N.LE.0 .OR. INCX.LE.0) RETURN IF (INCX.EQ.1) THEN * code for increment equal to 1 * * * clean-up loop * M = MOD(N,6) IF (M.NE.0) THEN DO I = 1,M STEMP = STEMP + ABS(SX(I)) END DO IF (N.LT.6) THEN SASUM = STEMP RETURN END IF END IF MP1 = M + 1 DO I = MP1,N,6 STEMP = STEMP + ABS(SX(I)) + ABS(SX(I+1)) + $ ABS(SX(I+2)) + ABS(SX(I+3)) + $ ABS(SX(I+4)) + ABS(SX(I+5)) END DO ELSE * * code for increment not equal to 1 * NINCX = N*INCX DO I = 1,NINCX,INCX STEMP = STEMP + ABS(SX(I)) END DO END IF SASUM = STEMP RETURN * * End of SASUM * END