NAME

drotmg - Construct a Gentleman's modified Given's plane rotation

SYNOPSIS

  SUBROUTINE DROTMG( D1, D2, B1, B2, PARAM)
  DOUBLE PRECISION D1, D2, B1, B2
  DOUBLE PRECISION PARAM(*)

  SUBROUTINE DROTMG_64( D1, D2, B1, B2, PARAM)
  DOUBLE PRECISION D1, D2, B1, B2
  DOUBLE PRECISION PARAM(*)

  SUBROUTINE ROTMG( D1, D2, B1, B2, PARAM)
  REAL(8) :: D1, D2, B1, B2
  REAL(8), DIMENSION(:) :: PARAM

  SUBROUTINE ROTMG_64( D1, D2, B1, B2, PARAM)
  REAL(8) :: D1, D2, B1, B2
  REAL(8), DIMENSION(:) :: PARAM

#include <sunperf.h>

void drotmg(double *d1, double *d2, double *b1, double *b2, double *param);

void drotmg_64(double *d1, double *d2, double *b1, double *b2, double *param);

drotmg Construct Gentleman's modified a Given's plane rotation that will annihilate an element of a vector.

D1 (input/output)
On entry, the first diagonal entry in the H matrix. On exit, changed to reflect the effect of the transformation.
D2 (input/output)
On entry, the second diagonal entry in the H matrix. On exit, changed to reflect the effect of the transformation.
B1 (input/output)
On entry, the first element of the vector to which the H matrix is applied. On exit, changed to reflect the effect of the transformation.
B2 (input/output)
On entry, the second element of the vector to which the H matrix is applied. Unchanged on exit.
PARAM (input/output)
On exit, PARAM(1) describes the form of the rotation matrix H, and PARAM(2..5) contain the H matrix.
If PARAM(1) = -2 then H = I and no elements of PARAM are modified.

If PARAM(1) = -1 then PARAM(2) = h11, PARAM(3) = h21, PARAM(4) = h12, and PARAM(5) = h22.

If PARAM(1) = 0 then h11 = h22 = 1, PARAM(3) = h21, and PARAM(4) = h12.

If PARAM(1) = 1 then h12 = 1, h21 = -1, PARAM(2) = h11, and PARAM(5) = h22.