Note: this is a BLAS routine and is not in libslatec.a
*DECK DROTM
SUBROUTINE DROTM (N, DX, INCX, DY, INCY, DPARAM)
C***BEGIN PROLOGUE DROTM
C***PURPOSE Apply a modified Givens transformation.
C***LIBRARY SLATEC (BLAS)
C***CATEGORY D1A8
C***TYPE DOUBLE PRECISION (SROTM-S, DROTM-D)
C***KEYWORDS BLAS, LINEAR ALGEBRA, MODIFIED GIVENS 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 DPARAM 5-element D.P. vector. DPARAM(1) is DFLAG described below.
C Locations 2-5 of SPARAM contain elements of the
C transformation matrix H described below.
C
C --Output--
C DX rotated vector (unchanged if N .LE. 0)
C DY rotated vector (unchanged if N .LE. 0)
C
C Apply the modified Givens transformation, H, to the 2 by N matrix
C (DX**T)
C (DY**T) , where **T indicates transpose. The elements of DX are
C in 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 With DPARAM(1)=DFLAG, H has one of the following forms:
C
C DFLAG=-1.D0 DFLAG=0.D0 DFLAG=1.D0 DFLAG=-2.D0
C
C (DH11 DH12) (1.D0 DH12) (DH11 1.D0) (1.D0 0.D0)
C H=( ) ( ) ( ) ( )
C (DH21 DH22), (DH21 1.D0), (-1.D0 DH22), (0.D0 1.D0).
C
C See DROTMG for a description of data storage in DPARAM.
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 DROTM