Note: this is a BLAS routine and is not in libslatec.a
*DECK DROT
SUBROUTINE DROT (N, DX, INCX, DY, INCY, DC, DS)
C***BEGIN PROLOGUE DROT
C***PURPOSE Apply a plane Givens rotation.
C***LIBRARY SLATEC (BLAS)
C***CATEGORY D1A8
C***TYPE DOUBLE PRECISION (SROT-S, DROT-D, CSROT-C)
C***KEYWORDS BLAS, GIVENS ROTATION, GIVENS TRANSFORMATION,
C LINEAR ALGEBRA, PLANE ROTATION, VECTOR
C***AUTHOR Lawson, C. L., (JPL)
C Hanson, R. J., (SNLA)
C Kincaid, D. R., (U. of Texas)
C Krogh, F. T., (JPL)
C***DESCRIPTION
C
C B L A S Subprogram
C Description of Parameters
C
C --Input--
C N number of elements in input vector(s)
C DX double precision vector with N elements
C INCX storage spacing between elements of DX
C DY double precision vector with N elements
C INCY storage spacing between elements of DY
C DC D.P. element of rotation matrix
C DS D.P. element of rotation matrix
C
C --Output--
C DX rotated vector DX (unchanged if N .LE. 0)
C DY rotated vector DY (unchanged if N .LE. 0)
C
C Multiply the 2 x 2 matrix ( DC DS) times the 2 x N matrix (DX**T)
C (-DS DC) (DY**T)
C where **T indicates transpose. The elements of DX are in
C DX(LX+I*INCX), I = 0 to N-1, where LX = 1 if INCX .GE. 0, else
C LX = 1+(1-N)*INCX, and similarly for DY using LY and INCY.
C
C***REFERENCES C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
C Krogh, Basic linear algebra subprograms for Fortran
C usage, Algorithm No. 539, Transactions on Mathematical
C Software 5, 3 (September 1979), pp. 308-323.
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 791001 DATE WRITTEN
C 861211 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 920310 Corrected definition of LX in DESCRIPTION. (WRB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE DROT