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LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
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00001 *> \brief \b SDOT 00002 * 00003 * =========== DOCUMENTATION =========== 00004 * 00005 * Online html documentation available at 00006 * http://www.netlib.org/lapack/explore-html/ 00007 * 00008 * Definition: 00009 * =========== 00010 * 00011 * REAL FUNCTION SDOT(N,SX,INCX,SY,INCY) 00012 * 00013 * .. Scalar Arguments .. 00014 * INTEGER INCX,INCY,N 00015 * .. 00016 * .. Array Arguments .. 00017 * REAL SX(*),SY(*) 00018 * .. 00019 * 00020 * 00021 *> \par Purpose: 00022 * ============= 00023 *> 00024 *> \verbatim 00025 *> 00026 *> SDOT forms the dot product of two vectors. 00027 *> uses unrolled loops for increments equal to one. 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 single_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 REAL FUNCTION SDOT(N,SX,INCX,SY,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 INTEGER INCX,INCY,N 00061 * .. 00062 * .. Array Arguments .. 00063 REAL SX(*),SY(*) 00064 * .. 00065 * 00066 * ===================================================================== 00067 * 00068 * .. Local Scalars .. 00069 REAL STEMP 00070 INTEGER I,IX,IY,M,MP1 00071 * .. 00072 * .. Intrinsic Functions .. 00073 INTRINSIC MOD 00074 * .. 00075 STEMP = 0.0e0 00076 SDOT = 0.0e0 00077 IF (N.LE.0) RETURN 00078 IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN 00079 * 00080 * code for both increments equal to 1 00081 * 00082 * 00083 * clean-up loop 00084 * 00085 M = MOD(N,5) 00086 IF (M.NE.0) THEN 00087 DO I = 1,M 00088 STEMP = STEMP + SX(I)*SY(I) 00089 END DO 00090 IF (N.LT.5) THEN 00091 SDOT=STEMP 00092 RETURN 00093 END IF 00094 END IF 00095 MP1 = M + 1 00096 DO I = MP1,N,5 00097 STEMP = STEMP + SX(I)*SY(I) + SX(I+1)*SY(I+1) + 00098 $ SX(I+2)*SY(I+2) + SX(I+3)*SY(I+3) + SX(I+4)*SY(I+4) 00099 END DO 00100 ELSE 00101 * 00102 * code for unequal increments or equal increments 00103 * not equal to 1 00104 * 00105 IX = 1 00106 IY = 1 00107 IF (INCX.LT.0) IX = (-N+1)*INCX + 1 00108 IF (INCY.LT.0) IY = (-N+1)*INCY + 1 00109 DO I = 1,N 00110 STEMP = STEMP + SX(IX)*SY(IY) 00111 IX = IX + INCX 00112 IY = IY + INCY 00113 END DO 00114 END IF 00115 SDOT = STEMP 00116 RETURN 00117 END