/* slarft.f -- translated by f2c (version 20061008).
   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 "blaswrap.h"
#include "lapack_datatypes.h"

/* Table of constant values */

static integer c__1 = 1;
static real c_b8 = 0.f;

/* Subroutine */ void slarft_(char *direct, char *storev, integer *n, integer *k, real *v, integer *ldv, real *tau,
                              real *t, integer *ldt) {
  /* System generated locals */
  integer t_dim1, t_offset, v_dim1, v_offset, i__1, i__2, i__3;
  real r__1;

  /* Local variables */
  integer i__, j, prevlastv;
  real vii;
  extern logical lsame_(char *, char *);
  extern /* Subroutine */ void sgemv_(const char *, const integer *, const integer *, const real *, const real *,
                                      const integer *, const real *, const integer *, const real *, real *,
                                      const integer *);
  integer lastv;
  extern /* Subroutine */ void strmv_(const char *, const char *, const char *, const integer *, const real *,
                                      const integer *, real *, const integer *);

  /*  -- LAPACK auxiliary routine (version 3.2) -- */
  /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
  /*     November 2006 */

  /*     .. Scalar Arguments .. */
  /*     .. */
  /*     .. Array Arguments .. */
  /*     .. */

  /*  Purpose */
  /*  ======= */

  /*  SLARFT forms the triangular factor T of a real block reflector H */
  /*  of order n, which is defined as a product of k elementary reflectors. */

  /*  If DIRECT = 'F', H = H(1) H(2) . . . H(k) and T is upper triangular; */

  /*  If DIRECT = 'B', H = H(k) . . . H(2) H(1) and T is lower triangular. */

  /*  If STOREV = 'C', the vector which defines the elementary reflector */
  /*  H(i) is stored in the i-th column of the array V, and */

  /*     H  =  I - V * T * V' */

  /*  If STOREV = 'R', the vector which defines the elementary reflector */
  /*  H(i) is stored in the i-th row of the array V, and */

  /*     H  =  I - V' * T * V */

  /*  Arguments */
  /*  ========= */

  /*  DIRECT  (input) CHARACTER*1 */
  /*          Specifies the order in which the elementary reflectors are */
  /*          multiplied to form the block reflector: */
  /*          = 'F': H = H(1) H(2) . . . H(k) (Forward) */
  /*          = 'B': H = H(k) . . . H(2) H(1) (Backward) */

  /*  STOREV  (input) CHARACTER*1 */
  /*          Specifies how the vectors which define the elementary */
  /*          reflectors are stored (see also Further Details): */
  /*          = 'C': columnwise */
  /*          = 'R': rowwise */

  /*  N       (input) INTEGER */
  /*          The order of the block reflector H. N >= 0. */

  /*  K       (input) INTEGER */
  /*          The order of the triangular factor T (= the number of */
  /*          elementary reflectors). K >= 1. */

  /*  V       (input/output) REAL array, dimension */
  /*                               (LDV,K) if STOREV = 'C' */
  /*                               (LDV,N) if STOREV = 'R' */
  /*          The matrix V. See further details. */

  /*  LDV     (input) INTEGER */
  /*          The leading dimension of the array V. */
  /*          If STOREV = 'C', LDV >= max(1,N); if STOREV = 'R', LDV >= K. */

  /*  TAU     (input) REAL array, dimension (K) */
  /*          TAU(i) must contain the scalar factor of the elementary */
  /*          reflector H(i). */

  /*  T       (output) REAL array, dimension (LDT,K) */
  /*          The k by k triangular factor T of the block reflector. */
  /*          If DIRECT = 'F', T is upper triangular; if DIRECT = 'B', T is */
  /*          lower triangular. The rest of the array is not used. */

  /*  LDT     (input) INTEGER */
  /*          The leading dimension of the array T. LDT >= K. */

  /*  Further Details */
  /*  =============== */

  /*  The shape of the matrix V and the storage of the vectors which define */
  /*  the H(i) is best illustrated by the following example with n = 5 and */
  /*  k = 3. The elements equal to 1 are not stored; the corresponding */
  /*  array elements are modified but restored on exit. The rest of the */
  /*  array is not used. */

  /*  DIRECT = 'F' and STOREV = 'C':         DIRECT = 'F' and STOREV = 'R': */

  /*               V = (  1       )                 V = (  1 v1 v1 v1 v1 ) */
  /*                   ( v1  1    )                     (     1 v2 v2 v2 ) */
  /*                   ( v1 v2  1 )                     (        1 v3 v3 ) */
  /*                   ( v1 v2 v3 ) */
  /*                   ( v1 v2 v3 ) */

  /*  DIRECT = 'B' and STOREV = 'C':         DIRECT = 'B' and STOREV = 'R': */

  /*               V = ( v1 v2 v3 )                 V = ( v1 v1  1       ) */
  /*                   ( v1 v2 v3 )                     ( v2 v2 v2  1    ) */
  /*                   (  1 v2 v3 )                     ( v3 v3 v3 v3  1 ) */
  /*                   (     1 v3 ) */
  /*                   (        1 ) */

  /*  ===================================================================== */

  /*     .. Parameters .. */
  /*     .. */
  /*     .. Local Scalars .. */
  /*     .. */
  /*     .. External Subroutines .. */
  /*     .. */
  /*     .. External Functions .. */
  /*     .. */
  /*     .. Executable Statements .. */

  /*     Quick return if possible */

  /* Parameter adjustments */
  v_dim1 = *ldv;
  v_offset = 1 + v_dim1;
  v -= v_offset;
  --tau;
  t_dim1 = *ldt;
  t_offset = 1 + t_dim1;
  t -= t_offset;

  /* Function Body */
  if (*n == 0) {
    return;
  }

  if (lsame_(direct, "F")) {
    prevlastv = *n;
    i__1 = *k;
    for (i__ = 1; i__ <= i__1; ++i__) {
      prevlastv = max(i__, prevlastv);
      if (tau[i__] == 0.f) {
        /*              H(i)  =  I */

        i__2 = i__;
        for (j = 1; j <= i__2; ++j) {
          t[j + i__ * t_dim1] = 0.f;
          /* L10: */
        }
      } else {
        /*              general case */

        vii = v[i__ + i__ * v_dim1];
        v[i__ + i__ * v_dim1] = 1.f;
        if (lsame_(storev, "C")) {
          /*                 Skip any trailing zeros. */
          i__2 = i__ + 1;
          for (lastv = *n; lastv >= i__2; --lastv) {
            if (v[lastv + i__ * v_dim1] != 0.f) {
              break;
            }
          }
          j = min(lastv, prevlastv);

          /*                 T(1:i-1,i) := - tau(i) * V(i:j,1:i-1)' * V(i:j,i) */

          i__2 = j - i__ + 1;
          i__3 = i__ - 1;
          r__1 = -tau[i__];
          sgemv_("Transpose", &i__2, &i__3, &r__1, &v[i__ + v_dim1], ldv, &v[i__ + i__ * v_dim1], &c__1, &c_b8,
                 &t[i__ * t_dim1 + 1], &c__1);
        } else {
          /*                 Skip any trailing zeros. */
          i__2 = i__ + 1;
          for (lastv = *n; lastv >= i__2; --lastv) {
            if (v[i__ + lastv * v_dim1] != 0.f) {
              break;
            }
          }
          j = min(lastv, prevlastv);

          /*                 T(1:i-1,i) := - tau(i) * V(1:i-1,i:j) * V(i,i:j)' */

          i__2 = i__ - 1;
          i__3 = j - i__ + 1;
          r__1 = -tau[i__];
          sgemv_("No transpose", &i__2, &i__3, &r__1, &v[i__ * v_dim1 + 1], ldv, &v[i__ + i__ * v_dim1], ldv, &c_b8,
                 &t[i__ * t_dim1 + 1], &c__1);
        }
        v[i__ + i__ * v_dim1] = vii;

        /*              T(1:i-1,i) := T(1:i-1,1:i-1) * T(1:i-1,i) */

        i__2 = i__ - 1;
        strmv_("Upper", "No transpose", "Non-unit", &i__2, &t[t_offset], ldt, &t[i__ * t_dim1 + 1], &c__1);
        t[i__ + i__ * t_dim1] = tau[i__];
        if (i__ > 1) {
          prevlastv = max(prevlastv, lastv);
        } else {
          prevlastv = lastv;
        }
      }
      /* L20: */
    }
  } else {
    prevlastv = 1;
    for (i__ = *k; i__ >= 1; --i__) {
      if (tau[i__] == 0.f) {
        /*              H(i)  =  I */

        i__1 = *k;
        for (j = i__; j <= i__1; ++j) {
          t[j + i__ * t_dim1] = 0.f;
          /* L30: */
        }
      } else {
        /*              general case */

        if (i__ < *k) {
          if (lsame_(storev, "C")) {
            vii = v[*n - *k + i__ + i__ * v_dim1];
            v[*n - *k + i__ + i__ * v_dim1] = 1.f;
            /*                    Skip any leading zeros. */
            i__1 = i__ - 1;
            for (lastv = 1; lastv <= i__1; ++lastv) {
              if (v[lastv + i__ * v_dim1] != 0.f) {
                break;
              }
            }
            j = max(lastv, prevlastv);

            /*                    T(i+1:k,i) := */
            /*                            - tau(i) * V(j:n-k+i,i+1:k)' * V(j:n-k+i,i) */

            i__1 = *n - *k + i__ - j + 1;
            i__2 = *k - i__;
            r__1 = -tau[i__];
            sgemv_("Transpose", &i__1, &i__2, &r__1, &v[j + (i__ + 1) * v_dim1], ldv, &v[j + i__ * v_dim1], &c__1,
                   &c_b8, &t[i__ + 1 + i__ * t_dim1], &c__1);
            v[*n - *k + i__ + i__ * v_dim1] = vii;
          } else {
            vii = v[i__ + (*n - *k + i__) * v_dim1];
            v[i__ + (*n - *k + i__) * v_dim1] = 1.f;
            /*                    Skip any leading zeros. */
            i__1 = i__ - 1;
            for (lastv = 1; lastv <= i__1; ++lastv) {
              if (v[i__ + lastv * v_dim1] != 0.f) {
                break;
              }
            }
            j = max(lastv, prevlastv);

            /*                    T(i+1:k,i) := */
            /*                            - tau(i) * V(i+1:k,j:n-k+i) * V(i,j:n-k+i)' */

            i__1 = *k - i__;
            i__2 = *n - *k + i__ - j + 1;
            r__1 = -tau[i__];
            sgemv_("No transpose", &i__1, &i__2, &r__1, &v[i__ + 1 + j * v_dim1], ldv, &v[i__ + j * v_dim1], ldv, &c_b8,
                   &t[i__ + 1 + i__ * t_dim1], &c__1);
            v[i__ + (*n - *k + i__) * v_dim1] = vii;
          }

          /*                 T(i+1:k,i) := T(i+1:k,i+1:k) * T(i+1:k,i) */

          i__1 = *k - i__;
          strmv_("Lower", "No transpose", "Non-unit", &i__1, &t[i__ + 1 + (i__ + 1) * t_dim1], ldt,
                 &t[i__ + 1 + i__ * t_dim1], &c__1);
          if (i__ > 1) {
            prevlastv = min(prevlastv, lastv);
          } else {
            prevlastv = lastv;
          }
        }
        t[i__ + i__ * t_dim1] = tau[i__];
      }
      /* L40: */
    }
  }

  /*     End of SLARFT */

} /* slarft_ */