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dot(3) LAPACK dot(3)

NAME

dot - dot: x^H x and x^T x

SYNOPSIS

Functions


complex function cdotc (n, cx, incx, cy, incy)
CDOTC complex function cdotu (n, cx, incx, cy, incy)
CDOTU double precision function ddot (n, dx, incx, dy, incy)
DDOT double precision function dsdot (n, sx, incx, sy, incy)
DSDOT real function sdot (n, sx, incx, sy, incy)
SDOT real function sdsdot (n, sb, sx, incx, sy, incy)
SDSDOT complex *16 function zdotc (n, zx, incx, zy, incy)
ZDOTC complex *16 function zdotu (n, zx, incx, zy, incy)
ZDOTU

Detailed Description

Function Documentation

complex function cdotc (integer n, complex, dimension(*) cx, integer incx, complex, dimension(*) cy, integer incy)

CDOTC

Purpose:


CDOTC forms the dot product of two complex vectors
CDOTC = X^H * Y

Parameters

N


N is INTEGER
number of elements in input vector(s)

CX


CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of CX

CY


CY is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of CY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, linpack, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

complex function cdotu (integer n, complex, dimension(*) cx, integer incx, complex, dimension(*) cy, integer incy)

CDOTU

Purpose:


CDOTU forms the dot product of two complex vectors
CDOTU = X^T * Y

Parameters

N


N is INTEGER
number of elements in input vector(s)

CX


CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of CX

CY


CY is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of CY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, linpack, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

double precision function ddot (integer n, double precision, dimension(*) dx, integer incx, double precision, dimension(*) dy, integer incy)

DDOT

Purpose:


DDOT forms the dot product of two vectors.
uses unrolled loops for increments equal to one.

Parameters

N


N is INTEGER
number of elements in input vector(s)

DX


DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of DX

DY


DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of DY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, linpack, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

double precision function dsdot (integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy)

DSDOT

Purpose:


Compute the inner product of two vectors with extended
precision accumulation and result.
Returns D.P. dot product accumulated in D.P., for S.P. SX and SY
DSDOT = sum for I = 0 to N-1 of SX(LX+I*INCX) * SY(LY+I*INCY),
where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
defined in a similar way using INCY.

Parameters

N


N is INTEGER
number of elements in input vector(s)

SX


SX is REAL array, dimension(N)
single precision vector with N elements

INCX


INCX is INTEGER
storage spacing between elements of SX

SY


SY is REAL array, dimension(N)
single precision vector with N elements

INCY


INCY is INTEGER
storage spacing between elements of SY

Returns

DSDOT


DSDOT is DOUBLE PRECISION
DSDOT double precision dot product (zero if N.LE.0)

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


References:


C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
Krogh, Basic linear algebra subprograms for Fortran
usage, Algorithm No. 539, Transactions on Mathematical
Software 5, 3 (September 1979), pp. 308-323.
REVISION HISTORY (YYMMDD)
791001 DATE WRITTEN
890831 Modified array declarations. (WRB)
890831 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
920310 Corrected definition of LX in DESCRIPTION. (WRB)
920501 Reformatted the REFERENCES section. (WRB)
070118 Reformat to LAPACK style (JL)

real function sdot (integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy)

SDOT

Purpose:


SDOT forms the dot product of two vectors.
uses unrolled loops for increments equal to one.

Parameters

N


N is INTEGER
number of elements in input vector(s)

SX


SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of SX

SY


SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of SY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, linpack, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

real function sdsdot (integer n, real sb, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy)

SDSDOT

Purpose:


Compute the inner product of two vectors with extended
precision accumulation.
Returns S.P. result with dot product accumulated in D.P.
SDSDOT = SB + sum for I = 0 to N-1 of SX(LX+I*INCX)*SY(LY+I*INCY),
where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
defined in a similar way using INCY.

Parameters

N


N is INTEGER
number of elements in input vector(s)

SB


SB is REAL
single precision scalar to be added to inner product

SX


SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
single precision vector with N elements

INCX


INCX is INTEGER
storage spacing between elements of SX

SY


SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
single precision vector with N elements

INCY


INCY is INTEGER
storage spacing between elements of SY

Author

Lawson, C. L., (JPL), Hanson, R. J., (SNLA),

Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL)

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


REFERENCES
C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
Krogh, Basic linear algebra subprograms for Fortran
usage, Algorithm No. 539, Transactions on Mathematical
Software 5, 3 (September 1979), pp. 308-323.
REVISION HISTORY (YYMMDD)
791001 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890831 Modified array declarations. (WRB)
890831 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
920310 Corrected definition of LX in DESCRIPTION. (WRB)
920501 Reformatted the REFERENCES section. (WRB)
070118 Reformat to LAPACK coding style

complex*16 function zdotc (integer n, complex*16, dimension(*) zx, integer incx, complex*16, dimension(*) zy, integer incy)

ZDOTC

Purpose:


ZDOTC forms the dot product of two complex vectors
ZDOTC = X^H * Y

Parameters

N


N is INTEGER
number of elements in input vector(s)

ZX


ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of ZX

ZY


ZY is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of ZY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

complex*16 function zdotu (integer n, complex*16, dimension(*) zx, integer incx, complex*16, dimension(*) zy, integer incy)

ZDOTU

Purpose:


ZDOTU forms the dot product of two complex vectors
ZDOTU = X^T * Y

Parameters

N


N is INTEGER
number of elements in input vector(s)

ZX


ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX


INCX is INTEGER
storage spacing between elements of ZX

ZY


ZY is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY


INCY is INTEGER
storage spacing between elements of ZY

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:


jack dongarra, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)

Author

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