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SUBROUTINE DSET( N, ALPHA, X, INCX )
*
* -- PBLAS auxiliary routine (version 2.0) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory,
* and University of California, Berkeley.
* April 1, 1998
*
* .. Scalar Arguments ..
INTEGER INCX, N
DOUBLE PRECISION ALPHA
* ..
* .. Array Arguments ..
DOUBLE PRECISION X( * )
* ..
*
* Purpose
* =======
*
* DSET sets the entries of an n vector x to the scalar alpha.
*
* Arguments
* =========
*
* N (input) INTEGER
* On entry, N specifies the length of the vector x. N must be
* at least zero.
*
* ALPHA (input) DOUBLE PRECISION
* On entry, ALPHA specifies the scalar alpha.
*
* X (input/output) DOUBLE PRECISION array of dimension at least
* ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented
* array X must contain the vector x. On exit, entries of the
* incremented array X are set to alpha.
*
* INCX (input) INTEGER
* On entry, INCX specifies the increment for the elements of X.
* INCX must not be zero.
*
* -- Written on April 1, 1998 by
* Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, INFO, IX, M, MP1
* ..
* .. External Subroutines ..
EXTERNAL XERBLA
* ..
* .. Intrinsic Functions ..
INTRINSIC MOD
* ..
* .. Executable Statements ..
*
* Test the input parameters.
*
INFO = 0
IF( N.LT.0 ) THEN
INFO = 1
ELSE IF( INCX.EQ.0 ) THEN
INFO = 4
END IF
IF( INFO.NE.0 ) THEN
CALL XERBLA( 'DSET', INFO )
RETURN
END IF
*
* Quick return if possible.
*
IF( N.LE.0 )
$ RETURN
*
* Form x := alpha
*
IF( INCX.EQ.1 )
$ GO TO 20
*
* code for increments not equal to 1
*
* Set up the start point in X.
*
IF( INCX.GT.0 ) THEN
IX = 1
ELSE
IX = 1 - ( N - 1 ) * INCX
END IF
*
DO 10 I = 1, N
X( IX ) = ALPHA
IX = IX + INCX
10 CONTINUE
*
RETURN
*
* code for increment equal to 1
*
* clean-up loop
*
20 M = MOD( N, 4 )
*
IF( M.EQ.0 )
$ GO TO 40
*
DO 30 I = 1, M
X( I ) = ALPHA
30 CONTINUE
IF( N.LT.4 )
$ RETURN
*
40 MP1 = M + 1
DO 50 I = MP1, N, 4
X( I ) = ALPHA
X( I + 1 ) = ALPHA
X( I + 2 ) = ALPHA
X( I + 3 ) = ALPHA
50 CONTINUE
*
RETURN
*
* End of DSET
*
END
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