ZLARTG (3lapack)

generate a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ]

SYNOPSIS

  SUBROUTINE ZLARTG( F, G, CS, SN, R )

      DOUBLE         PRECISION CS

      COMPLEX*16     F, G, R, SN

PURPOSE

  ZLARTG generates a plane rotation so that
     [ -SN  CS  ]     [ G ]     [ 0 ]

  This is a faster version of the BLAS1 routine ZROTG, except for the
  following differences:
     F and G are unchanged on return.
     If G=0, then CS=1 and SN=0.
     If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
        floating point operations.

ARGUMENTS

  F       (input) COMPLEX*16
          The first component of vector to be rotated.

  G       (input) COMPLEX*16
          The second component of vector to be rotated.

  CS      (output) DOUBLE PRECISION
          The cosine of the rotation.

  SN      (output) COMPLEX*16
          The sine of the rotation.

  R       (output) COMPLEX*16
          The nonzero component of the rotated vector.