version 1.1.1.1, 2010/01/26 15:22:45
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version 1.16, 2023/08/07 08:38:42
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*> \brief \b DASUM |
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* |
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* =========== DOCUMENTATION =========== |
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* |
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* Online html documentation available at |
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* http://www.netlib.org/lapack/explore-html/ |
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* |
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* Definition: |
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* =========== |
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* |
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* DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX) |
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* |
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* .. Scalar Arguments .. |
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* INTEGER INCX,N |
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* .. |
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* .. Array Arguments .. |
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* DOUBLE PRECISION DX(*) |
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* .. |
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* |
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* |
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*> \par Purpose: |
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* ============= |
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*> |
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*> \verbatim |
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*> |
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*> DASUM takes the sum of the absolute values. |
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*> \endverbatim |
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* |
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* Arguments: |
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* ========== |
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* |
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*> \param[in] N |
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*> \verbatim |
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*> N is INTEGER |
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*> number of elements in input vector(s) |
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*> \endverbatim |
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*> |
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*> \param[in] DX |
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*> \verbatim |
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*> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) |
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*> \endverbatim |
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*> |
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*> \param[in] INCX |
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*> \verbatim |
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*> INCX is INTEGER |
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*> storage spacing between elements of DX |
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*> \endverbatim |
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* |
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* Authors: |
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* ======== |
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* |
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*> \author Univ. of Tennessee |
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*> \author Univ. of California Berkeley |
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*> \author Univ. of Colorado Denver |
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*> \author NAG Ltd. |
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* |
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*> \ingroup double_blas_level1 |
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* |
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*> \par Further Details: |
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* ===================== |
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*> |
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*> \verbatim |
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*> |
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*> jack dongarra, linpack, 3/11/78. |
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*> modified 3/93 to return if incx .le. 0. |
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*> modified 12/3/93, array(1) declarations changed to array(*) |
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*> \endverbatim |
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*> |
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* ===================================================================== |
DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX) |
DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX) |
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* |
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* -- Reference BLAS level1 routine -- |
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* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- |
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX,N |
INTEGER INCX,N |
* .. |
* .. |
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DOUBLE PRECISION DX(*) |
DOUBLE PRECISION DX(*) |
* .. |
* .. |
* |
* |
* Purpose |
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* ======= |
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* |
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* DASUM takes the sum of the absolute values. |
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* |
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* Further Details |
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* =============== |
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* |
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* jack dongarra, linpack, 3/11/78. |
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* modified 3/93 to return if incx .le. 0. |
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* modified 12/3/93, array(1) declarations changed to array(*) |
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* |
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* ===================================================================== |
* ===================================================================== |
* |
* |
* .. Local Scalars .. |
* .. Local Scalars .. |
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DASUM = 0.0d0 |
DASUM = 0.0d0 |
DTEMP = 0.0d0 |
DTEMP = 0.0d0 |
IF (N.LE.0 .OR. INCX.LE.0) RETURN |
IF (N.LE.0 .OR. INCX.LE.0) RETURN |
IF (INCX.EQ.1) GO TO 20 |
IF (INCX.EQ.1) THEN |
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* code for increment equal to 1 |
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* |
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* |
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* clean-up loop |
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* |
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M = MOD(N,6) |
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IF (M.NE.0) THEN |
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DO I = 1,M |
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DTEMP = DTEMP + DABS(DX(I)) |
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END DO |
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IF (N.LT.6) THEN |
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DASUM = DTEMP |
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RETURN |
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END IF |
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END IF |
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MP1 = M + 1 |
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DO I = MP1,N,6 |
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DTEMP = DTEMP + DABS(DX(I)) + DABS(DX(I+1)) + |
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$ DABS(DX(I+2)) + DABS(DX(I+3)) + |
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$ DABS(DX(I+4)) + DABS(DX(I+5)) |
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END DO |
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ELSE |
* |
* |
* code for increment not equal to 1 |
* code for increment not equal to 1 |
* |
* |
NINCX = N*INCX |
NINCX = N*INCX |
DO 10 I = 1,NINCX,INCX |
DO I = 1,NINCX,INCX |
DTEMP = DTEMP + DABS(DX(I)) |
DTEMP = DTEMP + DABS(DX(I)) |
10 CONTINUE |
END DO |
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END IF |
DASUM = DTEMP |
DASUM = DTEMP |
RETURN |
RETURN |
* |
* |
* code for increment equal to 1 |
* End of DASUM |
* |
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* |
* |
* clean-up loop |
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* |
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20 M = MOD(N,6) |
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IF (M.EQ.0) GO TO 40 |
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DO 30 I = 1,M |
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DTEMP = DTEMP + DABS(DX(I)) |
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30 CONTINUE |
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IF (N.LT.6) GO TO 60 |
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40 MP1 = M + 1 |
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DO 50 I = MP1,N,6 |
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DTEMP = DTEMP + DABS(DX(I)) + DABS(DX(I+1)) + DABS(DX(I+2)) + |
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+ DABS(DX(I+3)) + DABS(DX(I+4)) + DABS(DX(I+5)) |
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50 CONTINUE |
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60 DASUM = DTEMP |
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RETURN |
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END |
END |