sorgqr.c
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00001 /* sorgqr.f -- translated by f2c (version 20061008).
00002    You must link the resulting object file with libf2c:
00003         on Microsoft Windows system, link with libf2c.lib;
00004         on Linux or Unix systems, link with .../path/to/libf2c.a -lm
00005         or, if you install libf2c.a in a standard place, with -lf2c -lm
00006         -- in that order, at the end of the command line, as in
00007                 cc *.o -lf2c -lm
00008         Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
00009 
00010                 http://www.netlib.org/f2c/libf2c.zip
00011 */
00012 
00013 #include "f2c.h"
00014 #include "blaswrap.h"
00015 
00016 /* Table of constant values */
00017 
00018 static integer c__1 = 1;
00019 static integer c_n1 = -1;
00020 static integer c__3 = 3;
00021 static integer c__2 = 2;
00022 
00023 /* Subroutine */ int sorgqr_(integer *m, integer *n, integer *k, real *a, 
00024         integer *lda, real *tau, real *work, integer *lwork, integer *info)
00025 {
00026     /* System generated locals */
00027     integer a_dim1, a_offset, i__1, i__2, i__3;
00028 
00029     /* Local variables */
00030     integer i__, j, l, ib, nb, ki, kk, nx, iws, nbmin, iinfo;
00031     extern /* Subroutine */ int sorg2r_(integer *, integer *, integer *, real 
00032             *, integer *, real *, real *, integer *), slarfb_(char *, char *, 
00033             char *, char *, integer *, integer *, integer *, real *, integer *
00034 , real *, integer *, real *, integer *, real *, integer *), xerbla_(char *, integer *);
00035     extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
00036             integer *, integer *);
00037     extern /* Subroutine */ int slarft_(char *, char *, integer *, integer *, 
00038             real *, integer *, real *, real *, integer *);
00039     integer ldwork, lwkopt;
00040     logical lquery;
00041 
00042 
00043 /*  -- LAPACK routine (version 3.2) -- */
00044 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00045 /*     November 2006 */
00046 
00047 /*     .. Scalar Arguments .. */
00048 /*     .. */
00049 /*     .. Array Arguments .. */
00050 /*     .. */
00051 
00052 /*  Purpose */
00053 /*  ======= */
00054 
00055 /*  SORGQR generates an M-by-N real matrix Q with orthonormal columns, */
00056 /*  which is defined as the first N columns of a product of K elementary */
00057 /*  reflectors of order M */
00058 
00059 /*        Q  =  H(1) H(2) . . . H(k) */
00060 
00061 /*  as returned by SGEQRF. */
00062 
00063 /*  Arguments */
00064 /*  ========= */
00065 
00066 /*  M       (input) INTEGER */
00067 /*          The number of rows of the matrix Q. M >= 0. */
00068 
00069 /*  N       (input) INTEGER */
00070 /*          The number of columns of the matrix Q. M >= N >= 0. */
00071 
00072 /*  K       (input) INTEGER */
00073 /*          The number of elementary reflectors whose product defines the */
00074 /*          matrix Q. N >= K >= 0. */
00075 
00076 /*  A       (input/output) REAL array, dimension (LDA,N) */
00077 /*          On entry, the i-th column must contain the vector which */
00078 /*          defines the elementary reflector H(i), for i = 1,2,...,k, as */
00079 /*          returned by SGEQRF in the first k columns of its array */
00080 /*          argument A. */
00081 /*          On exit, the M-by-N matrix Q. */
00082 
00083 /*  LDA     (input) INTEGER */
00084 /*          The first dimension of the array A. LDA >= max(1,M). */
00085 
00086 /*  TAU     (input) REAL array, dimension (K) */
00087 /*          TAU(i) must contain the scalar factor of the elementary */
00088 /*          reflector H(i), as returned by SGEQRF. */
00089 
00090 /*  WORK    (workspace/output) REAL array, dimension (MAX(1,LWORK)) */
00091 /*          On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
00092 
00093 /*  LWORK   (input) INTEGER */
00094 /*          The dimension of the array WORK. LWORK >= max(1,N). */
00095 /*          For optimum performance LWORK >= N*NB, where NB is the */
00096 /*          optimal blocksize. */
00097 
00098 /*          If LWORK = -1, then a workspace query is assumed; the routine */
00099 /*          only calculates the optimal size of the WORK array, returns */
00100 /*          this value as the first entry of the WORK array, and no error */
00101 /*          message related to LWORK is issued by XERBLA. */
00102 
00103 /*  INFO    (output) INTEGER */
00104 /*          = 0:  successful exit */
00105 /*          < 0:  if INFO = -i, the i-th argument has an illegal value */
00106 
00107 /*  ===================================================================== */
00108 
00109 /*     .. Parameters .. */
00110 /*     .. */
00111 /*     .. Local Scalars .. */
00112 /*     .. */
00113 /*     .. External Subroutines .. */
00114 /*     .. */
00115 /*     .. Intrinsic Functions .. */
00116 /*     .. */
00117 /*     .. External Functions .. */
00118 /*     .. */
00119 /*     .. Executable Statements .. */
00120 
00121 /*     Test the input arguments */
00122 
00123     /* Parameter adjustments */
00124     a_dim1 = *lda;
00125     a_offset = 1 + a_dim1;
00126     a -= a_offset;
00127     --tau;
00128     --work;
00129 
00130     /* Function Body */
00131     *info = 0;
00132     nb = ilaenv_(&c__1, "SORGQR", " ", m, n, k, &c_n1);
00133     lwkopt = max(1,*n) * nb;
00134     work[1] = (real) lwkopt;
00135     lquery = *lwork == -1;
00136     if (*m < 0) {
00137         *info = -1;
00138     } else if (*n < 0 || *n > *m) {
00139         *info = -2;
00140     } else if (*k < 0 || *k > *n) {
00141         *info = -3;
00142     } else if (*lda < max(1,*m)) {
00143         *info = -5;
00144     } else if (*lwork < max(1,*n) && ! lquery) {
00145         *info = -8;
00146     }
00147     if (*info != 0) {
00148         i__1 = -(*info);
00149         xerbla_("SORGQR", &i__1);
00150         return 0;
00151     } else if (lquery) {
00152         return 0;
00153     }
00154 
00155 /*     Quick return if possible */
00156 
00157     if (*n <= 0) {
00158         work[1] = 1.f;
00159         return 0;
00160     }
00161 
00162     nbmin = 2;
00163     nx = 0;
00164     iws = *n;
00165     if (nb > 1 && nb < *k) {
00166 
00167 /*        Determine when to cross over from blocked to unblocked code. */
00168 
00169 /* Computing MAX */
00170         i__1 = 0, i__2 = ilaenv_(&c__3, "SORGQR", " ", m, n, k, &c_n1);
00171         nx = max(i__1,i__2);
00172         if (nx < *k) {
00173 
00174 /*           Determine if workspace is large enough for blocked code. */
00175 
00176             ldwork = *n;
00177             iws = ldwork * nb;
00178             if (*lwork < iws) {
00179 
00180 /*              Not enough workspace to use optimal NB:  reduce NB and */
00181 /*              determine the minimum value of NB. */
00182 
00183                 nb = *lwork / ldwork;
00184 /* Computing MAX */
00185                 i__1 = 2, i__2 = ilaenv_(&c__2, "SORGQR", " ", m, n, k, &c_n1);
00186                 nbmin = max(i__1,i__2);
00187             }
00188         }
00189     }
00190 
00191     if (nb >= nbmin && nb < *k && nx < *k) {
00192 
00193 /*        Use blocked code after the last block. */
00194 /*        The first kk columns are handled by the block method. */
00195 
00196         ki = (*k - nx - 1) / nb * nb;
00197 /* Computing MIN */
00198         i__1 = *k, i__2 = ki + nb;
00199         kk = min(i__1,i__2);
00200 
00201 /*        Set A(1:kk,kk+1:n) to zero. */
00202 
00203         i__1 = *n;
00204         for (j = kk + 1; j <= i__1; ++j) {
00205             i__2 = kk;
00206             for (i__ = 1; i__ <= i__2; ++i__) {
00207                 a[i__ + j * a_dim1] = 0.f;
00208 /* L10: */
00209             }
00210 /* L20: */
00211         }
00212     } else {
00213         kk = 0;
00214     }
00215 
00216 /*     Use unblocked code for the last or only block. */
00217 
00218     if (kk < *n) {
00219         i__1 = *m - kk;
00220         i__2 = *n - kk;
00221         i__3 = *k - kk;
00222         sorg2r_(&i__1, &i__2, &i__3, &a[kk + 1 + (kk + 1) * a_dim1], lda, &
00223                 tau[kk + 1], &work[1], &iinfo);
00224     }
00225 
00226     if (kk > 0) {
00227 
00228 /*        Use blocked code */
00229 
00230         i__1 = -nb;
00231         for (i__ = ki + 1; i__1 < 0 ? i__ >= 1 : i__ <= 1; i__ += i__1) {
00232 /* Computing MIN */
00233             i__2 = nb, i__3 = *k - i__ + 1;
00234             ib = min(i__2,i__3);
00235             if (i__ + ib <= *n) {
00236 
00237 /*              Form the triangular factor of the block reflector */
00238 /*              H = H(i) H(i+1) . . . H(i+ib-1) */
00239 
00240                 i__2 = *m - i__ + 1;
00241                 slarft_("Forward", "Columnwise", &i__2, &ib, &a[i__ + i__ * 
00242                         a_dim1], lda, &tau[i__], &work[1], &ldwork);
00243 
00244 /*              Apply H to A(i:m,i+ib:n) from the left */
00245 
00246                 i__2 = *m - i__ + 1;
00247                 i__3 = *n - i__ - ib + 1;
00248                 slarfb_("Left", "No transpose", "Forward", "Columnwise", &
00249                         i__2, &i__3, &ib, &a[i__ + i__ * a_dim1], lda, &work[
00250                         1], &ldwork, &a[i__ + (i__ + ib) * a_dim1], lda, &
00251                         work[ib + 1], &ldwork);
00252             }
00253 
00254 /*           Apply H to rows i:m of current block */
00255 
00256             i__2 = *m - i__ + 1;
00257             sorg2r_(&i__2, &ib, &ib, &a[i__ + i__ * a_dim1], lda, &tau[i__], &
00258                     work[1], &iinfo);
00259 
00260 /*           Set rows 1:i-1 of current block to zero */
00261 
00262             i__2 = i__ + ib - 1;
00263             for (j = i__; j <= i__2; ++j) {
00264                 i__3 = i__ - 1;
00265                 for (l = 1; l <= i__3; ++l) {
00266                     a[l + j * a_dim1] = 0.f;
00267 /* L30: */
00268                 }
00269 /* L40: */
00270             }
00271 /* L50: */
00272         }
00273     }
00274 
00275     work[1] = (real) iws;
00276     return 0;
00277 
00278 /*     End of SORGQR */
00279 
00280 } /* sorgqr_ */


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autogenerated on Sat Jun 8 2019 18:56:12