rotmg(3F)

NAME
     drotmg, srotmg - BLAS Level-1. Compute the elements of a modified Givens
     plane rotation.

FORTRAN SYNOPSIS
     subroutine drotmg( d1, d2, x1, y1, param )
     double precision   d1, d2, x1, y1
     double precision   param( 5 )

     subroutine srotmg( d1, d2, x1, y1, param )
     real               d1, d2, x1, y1
     real               param( 5 )


DESCRIPTION
     DROTMG and SROTMG compute the elements of a modified Givens rotation
     matrix.


PARAMETERS
     d1      (input/output)
             On input, this value is the first diagonal element of the scaling
             matrix D.  On first call to DROTMG or SROTMG, this value is
             typically 1.0. Subsequent calls typically use the value from the
             previous call.
             On output, this value is the first diagonal element of the
             updated scaling matrix D'.

     d2      (input/output)
             On input, this value is the second diagonal element of the
             scaling matrix D.  On first call to DROTMG or SROTMG, this value
             is typically 1.0. Subsequent calls typically use the value from
             the previous call.
             On output, this value is the first diagonal element of the
             updated scaling matrix D'.

     x1      (input/output)
             On input, this value is the x-coordinate of the vector used to
             define the angle of rotation before scaling (multiplying by the
             matrix D).
             On output, this value is the x-coordinate of the rotated vector
             before scaling (multiplying by the matrix D').

     y1      (input/output)
             On input, this value is the y-coordinate of the vector used to
             define the angle of rotation before scaling (multiplying by the
             matrix D).
             On output, this value is the y coordinate of the rotated vecttor
             before scaling (multiplying by the matrix D').
     param   (output)
             This array contains rotation matrix information. DROTMG or SROTMG
             set up the computed elements in param from inputs d1, d2, x1, and
             y1.


SEE ALSO
     DROTM or SROTM.