LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
caxpy.f
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00001 *> \brief \b CAXPY
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE CAXPY(N,CA,CX,INCX,CY,INCY)
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       COMPLEX CA
00015 *       INTEGER INCX,INCY,N
00016 *       ..
00017 *       .. Array Arguments ..
00018 *       COMPLEX CX(*),CY(*)
00019 *       ..
00020 *  
00021 *
00022 *> \par Purpose:
00023 *  =============
00024 *>
00025 *> \verbatim
00026 *>
00027 *>    CAXPY constant times a vector plus a vector.
00028 *> \endverbatim
00029 *
00030 *  Authors:
00031 *  ========
00032 *
00033 *> \author Univ. of Tennessee 
00034 *> \author Univ. of California Berkeley 
00035 *> \author Univ. of Colorado Denver 
00036 *> \author NAG Ltd. 
00037 *
00038 *> \date November 2011
00039 *
00040 *> \ingroup complex_blas_level1
00041 *
00042 *> \par Further Details:
00043 *  =====================
00044 *>
00045 *> \verbatim
00046 *>
00047 *>     jack dongarra, linpack, 3/11/78.
00048 *>     modified 12/3/93, array(1) declarations changed to array(*)
00049 *> \endverbatim
00050 *>
00051 *  =====================================================================
00052       SUBROUTINE CAXPY(N,CA,CX,INCX,CY,INCY)
00053 *
00054 *  -- Reference BLAS level1 routine (version 3.4.0) --
00055 *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
00056 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00057 *     November 2011
00058 *
00059 *     .. Scalar Arguments ..
00060       COMPLEX CA
00061       INTEGER INCX,INCY,N
00062 *     ..
00063 *     .. Array Arguments ..
00064       COMPLEX CX(*),CY(*)
00065 *     ..
00066 *
00067 *  =====================================================================
00068 *
00069 *     .. Local Scalars ..
00070       INTEGER I,IX,IY
00071 *     ..
00072 *     .. External Functions ..
00073       REAL SCABS1
00074       EXTERNAL SCABS1
00075 *     ..
00076       IF (N.LE.0) RETURN
00077       IF (SCABS1(CA).EQ.0.0E+0) RETURN
00078       IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
00079 *
00080 *        code for both increments equal to 1
00081 *
00082          DO I = 1,N
00083             CY(I) = CY(I) + CA*CX(I)
00084          END DO
00085       ELSE
00086 *
00087 *        code for unequal increments or equal increments
00088 *          not equal to 1
00089 *
00090          IX = 1
00091          IY = 1
00092          IF (INCX.LT.0) IX = (-N+1)*INCX + 1
00093          IF (INCY.LT.0) IY = (-N+1)*INCY + 1
00094          DO I = 1,N
00095             CY(IY) = CY(IY) + CA*CX(IX)
00096             IX = IX + INCX
00097             IY = IY + INCY
00098          END DO
00099       END IF
00100 *
00101       RETURN
00102       END
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