DOKK / manpages / debian 13 / liblapack-doc / rotm.3.en
rotm(3) LAPACK rotm(3)

rotm - rotm: apply modified (fast) plane rotation


subroutine drotm (n, dx, incx, dy, incy, dparam)
DROTM subroutine srotm (n, sx, incx, sy, incy, sparam)
SROTM

_dimension(5)_dparam)">_dparam)">subroutine drotm (integer n, double precision, dimension(*) dx, integer incx, double precision, dimension(*) dy, integer incy, double precision, dimension(5) dparam)

DROTM

Purpose:



    APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX


    (DX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF DX ARE IN


    (DY**T)


    DX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE


    LX = (-INCX)*N, AND SIMILARLY FOR SY USING LY AND INCY.


    WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..


    DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0


      (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)


    H=(          )    (          )    (          )    (          )


      (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).


    SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM.

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

DPARAM



          DPARAM is DOUBLE PRECISION array, dimension (5)


     DPARAM(1)=DFLAG


     DPARAM(2)=DH11


     DPARAM(3)=DH21


     DPARAM(4)=DH12


     DPARAM(5)=DH22

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

_dimension(5)_sparam)">_sparam)">subroutine srotm (integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy, real, dimension(5) sparam)

SROTM

Purpose:



    APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX


    (SX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF SX ARE IN


    (SX**T)


    SX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE


    LX = (-INCX)*N, AND SIMILARLY FOR SY USING USING LY AND INCY.


    WITH SPARAM(1)=SFLAG, H HAS ONE OF THE FOLLOWING FORMS..


    SFLAG=-1.E0     SFLAG=0.E0        SFLAG=1.E0     SFLAG=-2.E0


      (SH11  SH12)    (1.E0  SH12)    (SH11  1.E0)    (1.E0  0.E0)


    H=(          )    (          )    (          )    (          )


      (SH21  SH22),   (SH21  1.E0),   (-1.E0 SH22),   (0.E0  1.E0).


    SEE  SROTMG FOR A DESCRIPTION OF DATA STORAGE IN SPARAM.

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

SPARAM



          SPARAM is REAL array, dimension (5)


     SPARAM(1)=SFLAG


     SPARAM(2)=SH11


     SPARAM(3)=SH21


     SPARAM(4)=SH12


     SPARAM(5)=SH22

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

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