text: /* blas/drotg.f -- translated by f2c (version 20050501).
     You must link the resulting object file with libf2c:
          on Microsoft Windows system, link with libf2c.lib;
          on Linux or Unix systems, link with .../path/to/libf2c.a -lm
          or, if you install libf2c.a in a standard place, with -lf2c -lm
          -- in that order, at the end of the command line, as in
                  cc *.o -lf2c -lm
          Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
  
                  http://www.netlib.org/f2c/libf2c.zip
  */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  #include "v3p_netlib.h"
  
  /* Table of constant values */
  
  static doublereal c_b4 = 1.;
  
  /*<       subroutine drotg(da,db,c,s) >*/
  /* Subroutine */ int drotg_(doublereal *da, doublereal *db, doublereal *c__,
          doublereal *s)
  {
      /* System generated locals */
      doublereal d__1, d__2;
  
      /* Builtin functions */
      double sqrt(doublereal), d_sign(doublereal *, doublereal *);
  
      /* Local variables */
      doublereal r__, z__, roe, scale;
  
  
  /*     construct givens plane rotation. */
  /*     jack dongarra, linpack, 3/11/78. */
  
  /*<       double precision da,db,c,s,roe,scale,r,z >*/
  
  /*<       roe = db >*/
      roe = *db;
  /*<       if( dabs(da) .gt. dabs(db) ) roe = da >*/
      if (abs(*da) > abs(*db)) {
          roe = *da;
      }
  /*<       scale = dabs(da) + dabs(db) >*/
      scale = abs(*da) + abs(*db);
  /*<       if( scale .ne. 0.0d0 ) go to 10 >*/
      if (scale != 0.) {
          goto L10;
      }
  /*<          c = 1.0d0 >*/
      *c__ = 1.;
  /*<          s = 0.0d0 >*/
      *s = 0.;
  /*<          r = 0.0d0 >*/
      r__ = 0.;
  /*<          z = 0.0d0 >*/
      z__ = 0.;
  /*<          go to 20 >*/
      goto L20;
  /*<    10 r = scale*dsqrt((da/scale)**2 + (db/scale)**2) >*/
  L10:
  /* Computing 2nd power */
      d__1 = *da / scale;
  /* Computing 2nd power */
      d__2 = *db / scale;
      r__ = scale * sqrt(d__1 * d__1 + d__2 * d__2);
  /*<       r = dsign(1.0d0,roe)*r >*/
      r__ = d_sign(&c_b4, &roe) * r__;
  /*<       c = da/r >*/
      *c__ = *da / r__;
  /*<       s = db/r >*/
      *s = *db / r__;
  /*<       z = 1.0d0 >*/
      z__ = 1.;
  /*<       if( dabs(da) .gt. dabs(db) ) z = s >*/
      if (abs(*da) > abs(*db)) {
          z__ = *s;
      }
  /*<       if( dabs(db) .ge. dabs(da) .and. c .ne. 0.0d0 ) z = 1.0d0/c >*/
      if (abs(*db) >= abs(*da) && *c__ != 0.) {
          z__ = 1. / *c__;
      }
  /*<    20 da = r >*/
  L20:
      *da = r__;
  /*<       db = z >*/
      *db = z__;
  /*<       return >*/
      return 0;
  /*<       end >*/
  } /* drotg_ */
  
  #ifdef __cplusplus
          }
  #endif
  