text: /* ../netlib/chptrf.f -- translated by f2c (version 20100827). 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 */
  #include "FLA_f2c.h" /* Table of constant values */
  static integer c__1 = 1;
  /* > \brief \b CHPTRF */
  /* =========== DOCUMENTATION =========== */
  /* Online html documentation available at */
  /* http://www.netlib.org/lapack/explore-html/ */
  /* > \htmlonly */
  /* > Download CHPTRF + dependencies */
  /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/chptrf. f"> */
  /* > [TGZ]</a> */
  /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/chptrf. f"> */
  /* > [ZIP]</a> */
  /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/chptrf. f"> */
  /* > [TXT]</a> */
  /* > \endhtmlonly */
  /* Definition: */
  /* =========== */
  /* SUBROUTINE CHPTRF( UPLO, N, AP, IPIV, INFO ) */
  /* .. Scalar Arguments .. */
  /* CHARACTER UPLO */
  /* INTEGER INFO, N */
  /* .. */
  /* .. Array Arguments .. */
  /* INTEGER IPIV( * ) */
  /* COMPLEX AP( * ) */
  /* .. */
  /* > \par Purpose: */
  /* ============= */
  /* > */
  /* > \verbatim */
  /* > */
  /* > CHPTRF computes the factorization of a complex Hermitian packed */
  /* > matrix A using the Bunch-Kaufman diagonal pivoting method: */
  /* > */
  /* > A = U*D*U**H or A = L*D*L**H */
  /* > */
  /* > where U (or L) is a product of permutation and unit upper (lower) */
  /* > triangular matrices, and D is Hermitian and block diagonal with */
  /* > 1-by-1 and 2-by-2 diagonal blocks. */
  /* > \endverbatim */
  /* Arguments: */
  /* ========== */
  /* > \param[in] UPLO */
  /* > \verbatim */
  /* > UPLO is CHARACTER*1 */
  /* > = 'U': Upper triangle of A is stored;
  */
  /* > = 'L': Lower triangle of A is stored. */
  /* > \endverbatim */
  /* > */
  /* > \param[in] N */
  /* > \verbatim */
  /* > N is INTEGER */
  /* > The order of the matrix A. N >= 0. */
  /* > \endverbatim */
  /* > */
  /* > \param[in,out] AP */
  /* > \verbatim */
  /* > AP is COMPLEX array, dimension (N*(N+1)/2) */
  /* > On entry, the upper or lower triangle of the Hermitian matrix */
  /* > A, packed columnwise in a linear array. The j-th column of A */
  /* > is stored in the array AP as follows: */
  /* > if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
  */
  /* > if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. */
  /* > */
  /* > On exit, the block diagonal matrix D and the multipliers used */
  /* > to obtain the factor U or L, stored as a packed triangular */
  /* > matrix overwriting A (see below for further details). */
  /* > \endverbatim */
  /* > */
  /* > \param[out] IPIV */
  /* > \verbatim */
  /* > IPIV is INTEGER array, dimension (N) */
  /* > Details of the interchanges and the block structure of D. */
  /* > If IPIV(k) > 0, then rows and columns k and IPIV(k) were */
  /* > interchanged and D(k,k) is a 1-by-1 diagonal block. */
  /* > If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and */
  /* > columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k) */
  /* > is a 2-by-2 diagonal block. If UPLO = 'L' and IPIV(k) = */
  /* > IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were */
  /* > interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block. */
  /* > \endverbatim */
  /* > */
  /* > \param[out] INFO */
  /* > \verbatim */
  /* > INFO is INTEGER */
  /* > = 0: successful exit */
  /* > < 0: if INFO = -i, the i-th argument had an illegal value */
  /* > > 0: if INFO = i, D(i,i) is exactly zero. The factorization */
  /* > has been completed, but the block diagonal matrix D is */
  /* > exactly singular, and division by zero will occur if it */
  /* > is used to solve a system of equations. */
  /* > \endverbatim */
  /* Authors: */
  /* ======== */
  /* > \author Univ. of Tennessee */
  /* > \author Univ. of California Berkeley */
  /* > \author Univ. of Colorado Denver */
  /* > \author NAG Ltd. */
  /* > \date November 2011 */
  /* > \ingroup complexOTHERcomputational */
  /* > \par Further Details: */
  /* ===================== */
  /* > */
  /* > \verbatim */
  /* > */
  /* > If UPLO = 'U', then A = U*D*U**H, where */
  /* > U = P(n)*U(n)* ... *P(k)U(k)* ..., */
  /* > i.e., U is a product of terms P(k)*U(k), where k decreases from n to */
  /* > 1 in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1 */
  /* > and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as */
  /* > defined by IPIV(k), and U(k) is a unit upper triangular matrix, such */
  /* > that if the diagonal block D(k) is of order s (s = 1 or 2), then */
  /* > */
  /* > ( I v 0 ) k-s */
  /* > U(k) = ( 0 I 0 ) s */
  /* > ( 0 0 I ) n-k */
  /* > k-s s n-k */
  /* > */
  /* > If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k). */
  /* > If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k), */
  /* > and A(k,k), and v overwrites A(1:k-2,k-1:k). */
  /* > */
  /* > If UPLO = 'L', then A = L*D*L**H, where */
  /* > L = P(1)*L(1)* ... *P(k)*L(k)* ..., */
  /* > i.e., L is a product of terms P(k)*L(k), where k increases from 1 to */
  /* > n in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1 */
  /* > and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as */
  /* > defined by IPIV(k), and L(k) is a unit lower triangular matrix, such */
  /* > that if the diagonal block D(k) is of order s (s = 1 or 2), then */
  /* > */
  /* > ( I 0 0 ) k-1 */
  /* > L(k) = ( 0 I 0 ) s */
  /* > ( 0 v I ) n-k-s+1 */
  /* > k-1 s n-k-s+1 */
  /* > */
  /* > If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k). */
  /* > If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k), */
  /* > and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1). */
  /* > \endverbatim */
  /* > \par Contributors: */
  /* ================== */
  /* > */
  /* > J. Lewis, Boeing Computer Services Company */
  /* > */
  /* ===================================================================== */
  /* Subroutine */
  int chptrf_(char *uplo, integer *n, complex *ap, integer * ipiv, integer *info)
  {
      /* System generated locals */
      integer i__1, i__2, i__3, i__4, i__5, i__6;
      real r__1, r__2, r__3, r__4;
      complex q__1, q__2, q__3, q__4, q__5, q__6;
      /* Builtin functions */
      double sqrt(doublereal), r_imag(complex *);
      void r_cnjg(complex *, complex *);
      /* Local variables */
      real d__;
      integer i__, j, k;
      complex t;
      real r1, d11;
      complex d12;
      real d22;
      complex d21;
      integer kc, kk, kp;
      complex wk;
      integer kx;
      real tt;
      integer knc, kpc, npp;
      complex wkm1, wkp1;
      extern /* Subroutine */
      int chpr_(char *, integer *, real *, complex *, integer *, complex *);
      integer imax, jmax;
      real alpha;
      extern logical lsame_(char *, char *);
      extern /* Subroutine */
      int cswap_(integer *, complex *, integer *, complex *, integer *);
      integer kstep;
      logical upper;
      extern real slapy2_(real *, real *);
      real absakk;
      extern integer icamax_(integer *, complex *, integer *);
      extern /* Subroutine */
      int csscal_(integer *, real *, complex *, integer *), xerbla_(char *, integer *);
      real colmax, rowmax;
      /* -- LAPACK computational routine (version 3.4.0) -- */
      /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
      /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
      /* November 2011 */
      /* .. Scalar Arguments .. */
      /* .. */
      /* .. Array Arguments .. */
      /* .. */
      /* ===================================================================== */
      /* .. Parameters .. */
      /* .. */
      /* .. Local Scalars .. */
      /* .. */
      /* .. External Functions .. */
      /* .. */
      /* .. External Subroutines .. */
      /* .. */
      /* .. Intrinsic Functions .. */
      /* .. */
      /* .. Statement Functions .. */
      /* .. */
      /* .. Statement Function definitions .. */
      /* .. */
      /* .. Executable Statements .. */
      /* Test the input parameters. */
      /* Parameter adjustments */
      --ipiv;
      --ap;
      /* Function Body */
      *info = 0;
      upper = lsame_(uplo, "U");
      if (! upper && ! lsame_(uplo, "L"))
      {
          *info = -1;
      }
      else if (*n < 0)
      {
          *info = -2;
      }
      if (*info != 0)
      {
          i__1 = -(*info);
          xerbla_("CHPTRF", &i__1);
          return 0;
      }
      /* Initialize ALPHA for use in choosing pivot block size. */
      alpha = (sqrt(17.f) + 1.f) / 8.f;
      if (upper)
      {
          /* Factorize A as U*D*U**H using the upper triangle of A */
          /* K is the main loop index, decreasing from N to 1 in steps of */
          /* 1 or 2 */
          k = *n;
          kc = (*n - 1) * *n / 2 + 1;
  L10:
          knc = kc;
          /* If K < 1, exit from loop */
          if (k < 1)
          {
              goto L110;
          }
          kstep = 1;
          /* Determine rows and columns to be interchanged and whether */
          /* a 1-by-1 or 2-by-2 pivot block will be used */
          i__1 = kc + k - 1;
          absakk = (r__1 = ap[i__1].r, f2c_abs(r__1));
          /* IMAX is the row-index of the largest off-diagonal element in */
          /* column K, and COLMAX is its absolute value */
          if (k > 1)
          {
              i__1 = k - 1;
              imax = icamax_(&i__1, &ap[kc], &c__1);
              i__1 = kc + imax - 1;
              colmax = (r__1 = ap[i__1].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[kc + imax - 1]), f2c_abs(r__2));
          }
          else
          {
              colmax = 0.f;
          }
          if (max(absakk,colmax) == 0.f)
          {
              /* Column K is zero: set INFO and continue */
              if (*info == 0)
              {
                  *info = k;
              }
              kp = k;
              i__1 = kc + k - 1;
              i__2 = kc + k - 1;
              r__1 = ap[i__2].r;
              ap[i__1].r = r__1;
              ap[i__1].i = 0.f; // , expr subst
          }
          else
          {
              if (absakk >= alpha * colmax)
              {
                  /* no interchange, use 1-by-1 pivot block */
                  kp = k;
              }
              else
              {
                  /* JMAX is the column-index of the largest off-diagonal */
                  /* element in row IMAX, and ROWMAX is its absolute value */
                  rowmax = 0.f;
                  jmax = imax;
                  kx = imax * (imax + 1) / 2 + imax;
                  i__1 = k;
                  for (j = imax + 1;
                          j <= i__1;
                          ++j)
                  {
                      i__2 = kx;
                      if ((r__1 = ap[i__2].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[ kx]), f2c_abs(r__2)) > rowmax)
                      {
                          i__2 = kx;
                          rowmax = (r__1 = ap[i__2].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[kx]), f2c_abs(r__2));
                          jmax = j;
                      }
                      kx += j;
                      /* L20: */
                  }
                  kpc = (imax - 1) * imax / 2 + 1;
                  if (imax > 1)
                  {
                      i__1 = imax - 1;
                      jmax = icamax_(&i__1, &ap[kpc], &c__1);
                      /* Computing MAX */
                      i__1 = kpc + jmax - 1;
                      r__3 = rowmax;
                      r__4 = (r__1 = ap[i__1].r, f2c_abs(r__1)) + ( r__2 = r_imag(&ap[kpc + jmax - 1]), f2c_abs(r__2)); // , expr subst
                      rowmax = max(r__3,r__4);
                  }
                  if (absakk >= alpha * colmax * (colmax / rowmax))
                  {
                      /* no interchange, use 1-by-1 pivot block */
                      kp = k;
                  }
                  else /* if(complicated condition) */
                  {
                      i__1 = kpc + imax - 1;
                      if ((r__1 = ap[i__1].r, f2c_abs(r__1)) >= alpha * rowmax)
                      {
                          /* interchange rows and columns K and IMAX, use 1-by-1 */
                          /* pivot block */
                          kp = imax;
                      }
                      else
                      {
                          /* interchange rows and columns K-1 and IMAX, use 2-by-2 */
                          /* pivot block */
                          kp = imax;
                          kstep = 2;
                      }
                  }
              }
              kk = k - kstep + 1;
              if (kstep == 2)
              {
                  knc = knc - k + 1;
              }
              if (kp != kk)
              {
                  /* Interchange rows and columns KK and KP in the leading */
                  /* submatrix A(1:k,1:k) */
                  i__1 = kp - 1;
                  cswap_(&i__1, &ap[knc], &c__1, &ap[kpc], &c__1);
                  kx = kpc + kp - 1;
                  i__1 = kk - 1;
                  for (j = kp + 1;
                          j <= i__1;
                          ++j)
                  {
                      kx = kx + j - 1;
                      r_cnjg(&q__1, &ap[knc + j - 1]);
                      t.r = q__1.r;
                      t.i = q__1.i; // , expr subst
                      i__2 = knc + j - 1;
                      r_cnjg(&q__1, &ap[kx]);
                      ap[i__2].r = q__1.r;
                      ap[i__2].i = q__1.i; // , expr subst
                      i__2 = kx;
                      ap[i__2].r = t.r;
                      ap[i__2].i = t.i; // , expr subst
                      /* L30: */
                  }
                  i__1 = kx + kk - 1;
                  r_cnjg(&q__1, &ap[kx + kk - 1]);
                  ap[i__1].r = q__1.r;
                  ap[i__1].i = q__1.i; // , expr subst
                  i__1 = knc + kk - 1;
                  r1 = ap[i__1].r;
                  i__1 = knc + kk - 1;
                  i__2 = kpc + kp - 1;
                  r__1 = ap[i__2].r;
                  ap[i__1].r = r__1;
                  ap[i__1].i = 0.f; // , expr subst
                  i__1 = kpc + kp - 1;
                  ap[i__1].r = r1;
                  ap[i__1].i = 0.f; // , expr subst
                  if (kstep == 2)
                  {
                      i__1 = kc + k - 1;
                      i__2 = kc + k - 1;
                      r__1 = ap[i__2].r;
                      ap[i__1].r = r__1;
                      ap[i__1].i = 0.f; // , expr subst
                      i__1 = kc + k - 2;
                      t.r = ap[i__1].r;
                      t.i = ap[i__1].i; // , expr subst
                      i__1 = kc + k - 2;
                      i__2 = kc + kp - 1;
                      ap[i__1].r = ap[i__2].r;
                      ap[i__1].i = ap[i__2].i; // , expr subst
                      i__1 = kc + kp - 1;
                      ap[i__1].r = t.r;
                      ap[i__1].i = t.i; // , expr subst
                  }
              }
              else
              {
                  i__1 = kc + k - 1;
                  i__2 = kc + k - 1;
                  r__1 = ap[i__2].r;
                  ap[i__1].r = r__1;
                  ap[i__1].i = 0.f; // , expr subst
                  if (kstep == 2)
                  {
                      i__1 = kc - 1;
                      i__2 = kc - 1;
                      r__1 = ap[i__2].r;
                      ap[i__1].r = r__1;
                      ap[i__1].i = 0.f; // , expr subst
                  }
              }
              /* Update the leading submatrix */
              if (kstep == 1)
              {
                  /* 1-by-1 pivot block D(k): column k now holds */
                  /* W(k) = U(k)*D(k) */
                  /* where U(k) is the k-th column of U */
                  /* Perform a rank-1 update of A(1:k-1,1:k-1) as */
                  /* A := A - U(k)*D(k)*U(k)**H = A - W(k)*1/D(k)*W(k)**H */
                  i__1 = kc + k - 1;
                  r1 = 1.f / ap[i__1].r;
                  i__1 = k - 1;
                  r__1 = -r1;
                  chpr_(uplo, &i__1, &r__1, &ap[kc], &c__1, &ap[1]);
                  /* Store U(k) in column k */
                  i__1 = k - 1;
                  csscal_(&i__1, &r1, &ap[kc], &c__1);
              }
              else
              {
                  /* 2-by-2 pivot block D(k): columns k and k-1 now hold */
                  /* ( W(k-1) W(k) ) = ( U(k-1) U(k) )*D(k) */
                  /* where U(k) and U(k-1) are the k-th and (k-1)-th columns */
                  /* of U */
                  /* Perform a rank-2 update of A(1:k-2,1:k-2) as */
                  /* A := A - ( U(k-1) U(k) )*D(k)*( U(k-1) U(k) )**H */
                  /* = A - ( W(k-1) W(k) )*inv(D(k))*( W(k-1) W(k) )**H */
                  if (k > 2)
                  {
                      i__1 = k - 1 + (k - 1) * k / 2;
                      r__1 = ap[i__1].r;
                      r__2 = r_imag(&ap[k - 1 + (k - 1) * k / 2]);
                      d__ = slapy2_(&r__1, &r__2);
                      i__1 = k - 1 + (k - 2) * (k - 1) / 2;
                      d22 = ap[i__1].r / d__;
                      i__1 = k + (k - 1) * k / 2;
                      d11 = ap[i__1].r / d__;
                      tt = 1.f / (d11 * d22 - 1.f);
                      i__1 = k - 1 + (k - 1) * k / 2;
                      q__1.r = ap[i__1].r / d__;
                      q__1.i = ap[i__1].i / d__; // , expr subst
                      d12.r = q__1.r;
                      d12.i = q__1.i; // , expr subst
                      d__ = tt / d__;
                      for (j = k - 2;
                              j >= 1;
                              --j)
                      {
                          i__1 = j + (k - 2) * (k - 1) / 2;
                          q__3.r = d11 * ap[i__1].r;
                          q__3.i = d11 * ap[i__1].i; // , expr subst
                          r_cnjg(&q__5, &d12);
                          i__2 = j + (k - 1) * k / 2;
                          q__4.r = q__5.r * ap[i__2].r - q__5.i * ap[i__2].i;
                          q__4.i = q__5.r * ap[i__2].i + q__5.i * ap[ i__2].r; // , expr subst
                          q__2.r = q__3.r - q__4.r;
                          q__2.i = q__3.i - q__4.i; // , expr subst
                          q__1.r = d__ * q__2.r;
                          q__1.i = d__ * q__2.i; // , expr subst
                          wkm1.r = q__1.r;
                          wkm1.i = q__1.i; // , expr subst
                          i__1 = j + (k - 1) * k / 2;
                          q__3.r = d22 * ap[i__1].r;
                          q__3.i = d22 * ap[i__1].i; // , expr subst
                          i__2 = j + (k - 2) * (k - 1) / 2;
                          q__4.r = d12.r * ap[i__2].r - d12.i * ap[i__2].i;
                          q__4.i = d12.r * ap[i__2].i + d12.i * ap[i__2] .r; // , expr subst
                          q__2.r = q__3.r - q__4.r;
                          q__2.i = q__3.i - q__4.i; // , expr subst
                          q__1.r = d__ * q__2.r;
                          q__1.i = d__ * q__2.i; // , expr subst
                          wk.r = q__1.r;
                          wk.i = q__1.i; // , expr subst
                          for (i__ = j;
                                  i__ >= 1;
                                  --i__)
                          {
                              i__1 = i__ + (j - 1) * j / 2;
                              i__2 = i__ + (j - 1) * j / 2;
                              i__3 = i__ + (k - 1) * k / 2;
                              r_cnjg(&q__4, &wk);
                              q__3.r = ap[i__3].r * q__4.r - ap[i__3].i * q__4.i;
                              q__3.i = ap[i__3].r * q__4.i + ap[ i__3].i * q__4.r; // , expr subst
                              q__2.r = ap[i__2].r - q__3.r;
                              q__2.i = ap[i__2].i - q__3.i; // , expr subst
                              i__4 = i__ + (k - 2) * (k - 1) / 2;
                              r_cnjg(&q__6, &wkm1);
                              q__5.r = ap[i__4].r * q__6.r - ap[i__4].i * q__6.i;
                              q__5.i = ap[i__4].r * q__6.i + ap[ i__4].i * q__6.r; // , expr subst
                              q__1.r = q__2.r - q__5.r;
                              q__1.i = q__2.i - q__5.i; // , expr subst
                              ap[i__1].r = q__1.r;
                              ap[i__1].i = q__1.i; // , expr subst
                              /* L40: */
                          }
                          i__1 = j + (k - 1) * k / 2;
                          ap[i__1].r = wk.r;
                          ap[i__1].i = wk.i; // , expr subst
                          i__1 = j + (k - 2) * (k - 1) / 2;
                          ap[i__1].r = wkm1.r;
                          ap[i__1].i = wkm1.i; // , expr subst
                          i__1 = j + (j - 1) * j / 2;
                          i__2 = j + (j - 1) * j / 2;
                          r__1 = ap[i__2].r;
                          q__1.r = r__1;
                          q__1.i = 0.f; // , expr subst
                          ap[i__1].r = q__1.r;
                          ap[i__1].i = q__1.i; // , expr subst
                          /* L50: */
                      }
                  }
              }
          }
          /* Store details of the interchanges in IPIV */
          if (kstep == 1)
          {
              ipiv[k] = kp;
          }
          else
          {
              ipiv[k] = -kp;
              ipiv[k - 1] = -kp;
          }
          /* Decrease K and return to the start of the main loop */
          k -= kstep;
          kc = knc - k;
          goto L10;
      }
      else
      {
          /* Factorize A as L*D*L**H using the lower triangle of A */
          /* K is the main loop index, increasing from 1 to N in steps of */
          /* 1 or 2 */
          k = 1;
          kc = 1;
          npp = *n * (*n + 1) / 2;
  L60:
          knc = kc;
          /* If K > N, exit from loop */
          if (k > *n)
          {
              goto L110;
          }
          kstep = 1;
          /* Determine rows and columns to be interchanged and whether */
          /* a 1-by-1 or 2-by-2 pivot block will be used */
          i__1 = kc;
          absakk = (r__1 = ap[i__1].r, f2c_abs(r__1));
          /* IMAX is the row-index of the largest off-diagonal element in */
          /* column K, and COLMAX is its absolute value */
          if (k < *n)
          {
              i__1 = *n - k;
              imax = k + icamax_(&i__1, &ap[kc + 1], &c__1);
              i__1 = kc + imax - k;
              colmax = (r__1 = ap[i__1].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[kc + imax - k]), f2c_abs(r__2));
          }
          else
          {
              colmax = 0.f;
          }
          if (max(absakk,colmax) == 0.f)
          {
              /* Column K is zero: set INFO and continue */
              if (*info == 0)
              {
                  *info = k;
              }
              kp = k;
              i__1 = kc;
              i__2 = kc;
              r__1 = ap[i__2].r;
              ap[i__1].r = r__1;
              ap[i__1].i = 0.f; // , expr subst
          }
          else
          {
              if (absakk >= alpha * colmax)
              {
                  /* no interchange, use 1-by-1 pivot block */
                  kp = k;
              }
              else
              {
                  /* JMAX is the column-index of the largest off-diagonal */
                  /* element in row IMAX, and ROWMAX is its absolute value */
                  rowmax = 0.f;
                  kx = kc + imax - k;
                  i__1 = imax - 1;
                  for (j = k;
                          j <= i__1;
                          ++j)
                  {
                      i__2 = kx;
                      if ((r__1 = ap[i__2].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[ kx]), f2c_abs(r__2)) > rowmax)
                      {
                          i__2 = kx;
                          rowmax = (r__1 = ap[i__2].r, f2c_abs(r__1)) + (r__2 = r_imag(&ap[kx]), f2c_abs(r__2));
                          jmax = j;
                      }
                      kx = kx + *n - j;
                      /* L70: */
                  }
                  kpc = npp - (*n - imax + 1) * (*n - imax + 2) / 2 + 1;
                  if (imax < *n)
                  {
                      i__1 = *n - imax;
                      jmax = imax + icamax_(&i__1, &ap[kpc + 1], &c__1);
                      /* Computing MAX */
                      i__1 = kpc + jmax - imax;
                      r__3 = rowmax;
                      r__4 = (r__1 = ap[i__1].r, f2c_abs(r__1)) + ( r__2 = r_imag(&ap[kpc + jmax - imax]), f2c_abs(r__2)); // , expr subst
                      rowmax = max(r__3,r__4);
                  }
                  if (absakk >= alpha * colmax * (colmax / rowmax))
                  {
                      /* no interchange, use 1-by-1 pivot block */
                      kp = k;
                  }
                  else /* if(complicated condition) */
                  {
                      i__1 = kpc;
                      if ((r__1 = ap[i__1].r, f2c_abs(r__1)) >= alpha * rowmax)
                      {
                          /* interchange rows and columns K and IMAX, use 1-by-1 */
                          /* pivot block */
                          kp = imax;
                      }
                      else
                      {
                          /* interchange rows and columns K+1 and IMAX, use 2-by-2 */
                          /* pivot block */
                          kp = imax;
                          kstep = 2;
                      }
                  }
              }
              kk = k + kstep - 1;
              if (kstep == 2)
              {
                  knc = knc + *n - k + 1;
              }
              if (kp != kk)
              {
                  /* Interchange rows and columns KK and KP in the trailing */
                  /* submatrix A(k:n,k:n) */
                  if (kp < *n)
                  {
                      i__1 = *n - kp;
                      cswap_(&i__1, &ap[knc + kp - kk + 1], &c__1, &ap[kpc + 1], &c__1);
                  }
                  kx = knc + kp - kk;
                  i__1 = kp - 1;
                  for (j = kk + 1;
                          j <= i__1;
                          ++j)
                  {
                      kx = kx + *n - j + 1;
                      r_cnjg(&q__1, &ap[knc + j - kk]);
                      t.r = q__1.r;
                      t.i = q__1.i; // , expr subst
                      i__2 = knc + j - kk;
                      r_cnjg(&q__1, &ap[kx]);
                      ap[i__2].r = q__1.r;
                      ap[i__2].i = q__1.i; // , expr subst
                      i__2 = kx;
                      ap[i__2].r = t.r;
                      ap[i__2].i = t.i; // , expr subst
                      /* L80: */
                  }
                  i__1 = knc + kp - kk;
                  r_cnjg(&q__1, &ap[knc + kp - kk]);
                  ap[i__1].r = q__1.r;
                  ap[i__1].i = q__1.i; // , expr subst
                  i__1 = knc;
                  r1 = ap[i__1].r;
                  i__1 = knc;
                  i__2 = kpc;
                  r__1 = ap[i__2].r;
                  ap[i__1].r = r__1;
                  ap[i__1].i = 0.f; // , expr subst
                  i__1 = kpc;
                  ap[i__1].r = r1;
                  ap[i__1].i = 0.f; // , expr subst
                  if (kstep == 2)
                  {
                      i__1 = kc;
                      i__2 = kc;
                      r__1 = ap[i__2].r;
                      ap[i__1].r = r__1;
                      ap[i__1].i = 0.f; // , expr subst
                      i__1 = kc + 1;
                      t.r = ap[i__1].r;
                      t.i = ap[i__1].i; // , expr subst
                      i__1 = kc + 1;
                      i__2 = kc + kp - k;
                      ap[i__1].r = ap[i__2].r;
                      ap[i__1].i = ap[i__2].i; // , expr subst
                      i__1 = kc + kp - k;
                      ap[i__1].r = t.r;
                      ap[i__1].i = t.i; // , expr subst
                  }
              }
              else
              {
                  i__1 = kc;
                  i__2 = kc;
                  r__1 = ap[i__2].r;
                  ap[i__1].r = r__1;
                  ap[i__1].i = 0.f; // , expr subst
                  if (kstep == 2)
                  {
                      i__1 = knc;
                      i__2 = knc;
                      r__1 = ap[i__2].r;
                      ap[i__1].r = r__1;
                      ap[i__1].i = 0.f; // , expr subst
                  }
              }
              /* Update the trailing submatrix */
              if (kstep == 1)
              {
                  /* 1-by-1 pivot block D(k): column k now holds */
                  /* W(k) = L(k)*D(k) */
                  /* where L(k) is the k-th column of L */
                  if (k < *n)
                  {
                      /* Perform a rank-1 update of A(k+1:n,k+1:n) as */
                      /* A := A - L(k)*D(k)*L(k)**H = A - W(k)*(1/D(k))*W(k)**H */
                      i__1 = kc;
                      r1 = 1.f / ap[i__1].r;
                      i__1 = *n - k;
                      r__1 = -r1;
                      chpr_(uplo, &i__1, &r__1, &ap[kc + 1], &c__1, &ap[kc + *n - k + 1]);
                      /* Store L(k) in column K */
                      i__1 = *n - k;
                      csscal_(&i__1, &r1, &ap[kc + 1], &c__1);
                  }
              }
              else
              {
                  /* 2-by-2 pivot block D(k): columns K and K+1 now hold */
                  /* ( W(k) W(k+1) ) = ( L(k) L(k+1) )*D(k) */
                  /* where L(k) and L(k+1) are the k-th and (k+1)-th columns */
                  /* of L */
                  if (k < *n - 1)
                  {
                      /* Perform a rank-2 update of A(k+2:n,k+2:n) as */
                      /* A := A - ( L(k) L(k+1) )*D(k)*( L(k) L(k+1) )**H */
                      /* = A - ( W(k) W(k+1) )*inv(D(k))*( W(k) W(k+1) )**H */
                      /* where L(k) and L(k+1) are the k-th and (k+1)-th */
                      /* columns of L */
                      i__1 = k + 1 + (k - 1) * ((*n << 1) - k) / 2;
                      r__1 = ap[i__1].r;
                      r__2 = r_imag(&ap[k + 1 + (k - 1) * ((*n << 1) - k) / 2]);
                      d__ = slapy2_(&r__1, &r__2);
                      i__1 = k + 1 + k * ((*n << 1) - k - 1) / 2;
                      d11 = ap[i__1].r / d__;
                      i__1 = k + (k - 1) * ((*n << 1) - k) / 2;
                      d22 = ap[i__1].r / d__;
                      tt = 1.f / (d11 * d22 - 1.f);
                      i__1 = k + 1 + (k - 1) * ((*n << 1) - k) / 2;
                      q__1.r = ap[i__1].r / d__;
                      q__1.i = ap[i__1].i / d__; // , expr subst
                      d21.r = q__1.r;
                      d21.i = q__1.i; // , expr subst
                      d__ = tt / d__;
                      i__1 = *n;
                      for (j = k + 2;
                              j <= i__1;
                              ++j)
                      {
                          i__2 = j + (k - 1) * ((*n << 1) - k) / 2;
                          q__3.r = d11 * ap[i__2].r;
                          q__3.i = d11 * ap[i__2].i; // , expr subst
                          i__3 = j + k * ((*n << 1) - k - 1) / 2;
                          q__4.r = d21.r * ap[i__3].r - d21.i * ap[i__3].i;
                          q__4.i = d21.r * ap[i__3].i + d21.i * ap[i__3] .r; // , expr subst
                          q__2.r = q__3.r - q__4.r;
                          q__2.i = q__3.i - q__4.i; // , expr subst
                          q__1.r = d__ * q__2.r;
                          q__1.i = d__ * q__2.i; // , expr subst
                          wk.r = q__1.r;
                          wk.i = q__1.i; // , expr subst
                          i__2 = j + k * ((*n << 1) - k - 1) / 2;
                          q__3.r = d22 * ap[i__2].r;
                          q__3.i = d22 * ap[i__2].i; // , expr subst
                          r_cnjg(&q__5, &d21);
                          i__3 = j + (k - 1) * ((*n << 1) - k) / 2;
                          q__4.r = q__5.r * ap[i__3].r - q__5.i * ap[i__3].i;
                          q__4.i = q__5.r * ap[i__3].i + q__5.i * ap[ i__3].r; // , expr subst
                          q__2.r = q__3.r - q__4.r;
                          q__2.i = q__3.i - q__4.i; // , expr subst
                          q__1.r = d__ * q__2.r;
                          q__1.i = d__ * q__2.i; // , expr subst
                          wkp1.r = q__1.r;
                          wkp1.i = q__1.i; // , expr subst
                          i__2 = *n;
                          for (i__ = j;
                                  i__ <= i__2;
                                  ++i__)
                          {
                              i__3 = i__ + (j - 1) * ((*n << 1) - j) / 2;
                              i__4 = i__ + (j - 1) * ((*n << 1) - j) / 2;
                              i__5 = i__ + (k - 1) * ((*n << 1) - k) / 2;
                              r_cnjg(&q__4, &wk);
                              q__3.r = ap[i__5].r * q__4.r - ap[i__5].i * q__4.i;
                              q__3.i = ap[i__5].r * q__4.i + ap[ i__5].i * q__4.r; // , expr subst
                              q__2.r = ap[i__4].r - q__3.r;
                              q__2.i = ap[i__4].i - q__3.i; // , expr subst
                              i__6 = i__ + k * ((*n << 1) - k - 1) / 2;
                              r_cnjg(&q__6, &wkp1);
                              q__5.r = ap[i__6].r * q__6.r - ap[i__6].i * q__6.i;
                              q__5.i = ap[i__6].r * q__6.i + ap[ i__6].i * q__6.r; // , expr subst
                              q__1.r = q__2.r - q__5.r;
                              q__1.i = q__2.i - q__5.i; // , expr subst
                              ap[i__3].r = q__1.r;
                              ap[i__3].i = q__1.i; // , expr subst
                              /* L90: */
                          }
                          i__2 = j + (k - 1) * ((*n << 1) - k) / 2;
                          ap[i__2].r = wk.r;
                          ap[i__2].i = wk.i; // , expr subst
                          i__2 = j + k * ((*n << 1) - k - 1) / 2;
                          ap[i__2].r = wkp1.r;
                          ap[i__2].i = wkp1.i; // , expr subst
                          i__2 = j + (j - 1) * ((*n << 1) - j) / 2;
                          i__3 = j + (j - 1) * ((*n << 1) - j) / 2;
                          r__1 = ap[i__3].r;
                          q__1.r = r__1;
                          q__1.i = 0.f; // , expr subst
                          ap[i__2].r = q__1.r;
                          ap[i__2].i = q__1.i; // , expr subst
                          /* L100: */
                      }
                  }
              }
          }
          /* Store details of the interchanges in IPIV */
          if (kstep == 1)
          {
              ipiv[k] = kp;
          }
          else
          {
              ipiv[k] = -kp;
              ipiv[k + 1] = -kp;
          }
          /* Increase K and return to the start of the main loop */
          k += kstep;
          kc = knc + *n - k + 2;
          goto L60;
      }
  L110:
      return 0;
      /* End of CHPTRF */
  }
  /* chptrf_ */
  