_ROTMG(3F)_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').
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_ROTMG(3F)_ROTMG(3F)
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.
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