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dlartg

 NAME
      DLARTG - generate a plane rotation so that   [ CS SN ]

 SYNOPSIS
      SUBROUTINE DLARTG( F, G, CS, SN, R )

          DOUBLE         PRECISION CS, F, G, R, SN

 PURPOSE
      DLARTG generate a plane rotation so that
         [ -SN  CS  ]     [ G ]     [ 0 ]

      This is a faster version of the BLAS1 routine DROTG, 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 (saves work in DBDSQR when
            there are zeros on the diagonal).

 ARGUMENTS
      F       (input) DOUBLE PRECISION
              The first component of vector to be rotated.

      G       (input) DOUBLE PRECISION
              The second component of vector to be rotated.

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

      SN      (output) DOUBLE PRECISION
              The sine of the rotation.

      R       (output) DOUBLE PRECISION
              The nonzero component of the rotated vector.