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