cgelqs.c
Go to the documentation of this file.
00001 /* cgelqs.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 complex c_b1 = {0.f,0.f};
00019 static complex c_b2 = {1.f,0.f};
00020 
00021 /* Subroutine */ int cgelqs_(integer *m, integer *n, integer *nrhs, complex *
00022         a, integer *lda, complex *tau, complex *b, integer *ldb, complex *
00023         work, integer *lwork, integer *info)
00024 {
00025     /* System generated locals */
00026     integer a_dim1, a_offset, b_dim1, b_offset, i__1;
00027 
00028     /* Local variables */
00029     extern /* Subroutine */ int ctrsm_(char *, char *, char *, char *, 
00030             integer *, integer *, complex *, complex *, integer *, complex *, 
00031             integer *), claset_(char *, 
00032             integer *, integer *, complex *, complex *, complex *, integer *), xerbla_(char *, integer *), cunmlq_(char *, char 
00033             *, integer *, integer *, integer *, complex *, integer *, complex 
00034             *, complex *, integer *, complex *, integer *, integer *);
00035 
00036 
00037 /*  -- LAPACK routine (version 3.1) -- */
00038 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00039 /*     November 2006 */
00040 
00041 /*     .. Scalar Arguments .. */
00042 /*     .. */
00043 /*     .. Array Arguments .. */
00044 /*     .. */
00045 
00046 /*  Purpose */
00047 /*  ======= */
00048 
00049 /*  Compute a minimum-norm solution */
00050 /*      min || A*X - B || */
00051 /*  using the LQ factorization */
00052 /*      A = L*Q */
00053 /*  computed by CGELQF. */
00054 
00055 /*  Arguments */
00056 /*  ========= */
00057 
00058 /*  M       (input) INTEGER */
00059 /*          The number of rows of the matrix A.  M >= 0. */
00060 
00061 /*  N       (input) INTEGER */
00062 /*          The number of columns of the matrix A.  N >= M >= 0. */
00063 
00064 /*  NRHS    (input) INTEGER */
00065 /*          The number of columns of B.  NRHS >= 0. */
00066 
00067 /*  A       (input) COMPLEX array, dimension (LDA,N) */
00068 /*          Details of the LQ factorization of the original matrix A as */
00069 /*          returned by CGELQF. */
00070 
00071 /*  LDA     (input) INTEGER */
00072 /*          The leading dimension of the array A.  LDA >= M. */
00073 
00074 /*  TAU     (input) COMPLEX array, dimension (M) */
00075 /*          Details of the orthogonal matrix Q. */
00076 
00077 /*  B       (input/output) COMPLEX array, dimension (LDB,NRHS) */
00078 /*          On entry, the m-by-nrhs right hand side matrix B. */
00079 /*          On exit, the n-by-nrhs solution matrix X. */
00080 
00081 /*  LDB     (input) INTEGER */
00082 /*          The leading dimension of the array B. LDB >= N. */
00083 
00084 /*  WORK    (workspace) COMPLEX array, dimension (LWORK) */
00085 
00086 /*  LWORK   (input) INTEGER */
00087 /*          The length of the array WORK.  LWORK must be at least NRHS, */
00088 /*          and should be at least NRHS*NB, where NB is the block size */
00089 /*          for this environment. */
00090 
00091 /*  INFO    (output) INTEGER */
00092 /*          = 0: successful exit */
00093 /*          < 0: if INFO = -i, the i-th argument had an illegal value */
00094 
00095 /*  ===================================================================== */
00096 
00097 /*     .. Parameters .. */
00098 /*     .. */
00099 /*     .. External Subroutines .. */
00100 /*     .. */
00101 /*     .. Intrinsic Functions .. */
00102 /*     .. */
00103 /*     .. Executable Statements .. */
00104 
00105 /*     Test the input parameters. */
00106 
00107     /* Parameter adjustments */
00108     a_dim1 = *lda;
00109     a_offset = 1 + a_dim1;
00110     a -= a_offset;
00111     --tau;
00112     b_dim1 = *ldb;
00113     b_offset = 1 + b_dim1;
00114     b -= b_offset;
00115     --work;
00116 
00117     /* Function Body */
00118     *info = 0;
00119     if (*m < 0) {
00120         *info = -1;
00121     } else if (*n < 0 || *m > *n) {
00122         *info = -2;
00123     } else if (*nrhs < 0) {
00124         *info = -3;
00125     } else if (*lda < max(1,*m)) {
00126         *info = -5;
00127     } else if (*ldb < max(1,*n)) {
00128         *info = -8;
00129     } else if (*lwork < 1 || *lwork < *nrhs && *m > 0 && *n > 0) {
00130         *info = -10;
00131     }
00132     if (*info != 0) {
00133         i__1 = -(*info);
00134         xerbla_("CGELQS", &i__1);
00135         return 0;
00136     }
00137 
00138 /*     Quick return if possible */
00139 
00140     if (*n == 0 || *nrhs == 0 || *m == 0) {
00141         return 0;
00142     }
00143 
00144 /*     Solve L*X = B(1:m,:) */
00145 
00146     ctrsm_("Left", "Lower", "No transpose", "Non-unit", m, nrhs, &c_b2, &a[
00147             a_offset], lda, &b[b_offset], ldb);
00148 
00149 /*     Set B(m+1:n,:) to zero */
00150 
00151     if (*m < *n) {
00152         i__1 = *n - *m;
00153         claset_("Full", &i__1, nrhs, &c_b1, &c_b1, &b[*m + 1 + b_dim1], ldb);
00154     }
00155 
00156 /*     B := Q' * B */
00157 
00158     cunmlq_("Left", "Conjugate transpose", n, nrhs, m, &a[a_offset], lda, &
00159             tau[1], &b[b_offset], ldb, &work[1], lwork, info);
00160 
00161     return 0;
00162 
00163 /*     End of CGELQS */
00164 
00165 } /* cgelqs_ */


swiftnav
Author(s):
autogenerated on Sat Jun 8 2019 18:55:26