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#include "rb_lapack.h"
extern VOID sgehrd_(integer* n, integer* ilo, integer* ihi, real* a, integer* lda, real* tau, real* work, integer* lwork, integer* info);
static VALUE
rblapack_sgehrd(int argc, VALUE *argv, VALUE self){
VALUE rblapack_ilo;
integer ilo;
VALUE rblapack_ihi;
integer ihi;
VALUE rblapack_a;
real *a;
VALUE rblapack_lwork;
integer lwork;
VALUE rblapack_tau;
real *tau;
VALUE rblapack_work;
real *work;
VALUE rblapack_info;
integer info;
VALUE rblapack_a_out__;
real *a_out__;
integer lda;
integer n;
VALUE rblapack_options;
if (argc > 0 && TYPE(argv[argc-1]) == T_HASH) {
argc--;
rblapack_options = argv[argc];
if (rb_hash_aref(rblapack_options, sHelp) == Qtrue) {
printf("%s\n", "USAGE:\n tau, work, info, a = NumRu::Lapack.sgehrd( ilo, ihi, a, [:lwork => lwork, :usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n SUBROUTINE SGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO )\n\n* Purpose\n* =======\n*\n* SGEHRD reduces a real general matrix A to upper Hessenberg form H by\n* an orthogonal similarity transformation: Q' * A * Q = H .\n*\n\n* Arguments\n* =========\n*\n* N (input) INTEGER\n* The order of the matrix A. N >= 0.\n*\n* ILO (input) INTEGER\n* IHI (input) INTEGER\n* It is assumed that A is already upper triangular in rows\n* and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally\n* set by a previous call to SGEBAL; otherwise they should be\n* set to 1 and N respectively. See Further Details.\n* 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.\n*\n* A (input/output) REAL array, dimension (LDA,N)\n* On entry, the N-by-N general matrix to be reduced.\n* On exit, the upper triangle and the first subdiagonal of A\n* are overwritten with the upper Hessenberg matrix H, and the\n* elements below the first subdiagonal, with the array TAU,\n* represent the orthogonal matrix Q as a product of elementary\n* reflectors. See Further Details.\n*\n* LDA (input) INTEGER\n* The leading dimension of the array A. LDA >= max(1,N).\n*\n* TAU (output) REAL array, dimension (N-1)\n* The scalar factors of the elementary reflectors (see Further\n* Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to\n* zero.\n*\n* WORK (workspace/output) REAL array, dimension (LWORK)\n* On exit, if INFO = 0, WORK(1) returns the optimal LWORK.\n*\n* LWORK (input) INTEGER\n* The length of the array WORK. LWORK >= max(1,N).\n* For optimum performance LWORK >= N*NB, where NB is the\n* optimal blocksize.\n*\n* If LWORK = -1, then a workspace query is assumed; the routine\n* only calculates the optimal size of the WORK array, returns\n* this value as the first entry of the WORK array, and no error\n* message related to LWORK is issued by XERBLA.\n*\n* INFO (output) INTEGER\n* = 0: successful exit\n* < 0: if INFO = -i, the i-th argument had an illegal value.\n*\n\n* Further Details\n* ===============\n*\n* The matrix Q is represented as a product of (ihi-ilo) elementary\n* reflectors\n*\n* Q = H(ilo) H(ilo+1) . . . H(ihi-1).\n*\n* Each H(i) has the form\n*\n* H(i) = I - tau * v * v'\n*\n* where tau is a real scalar, and v is a real vector with\n* v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on\n* exit in A(i+2:ihi,i), and tau in TAU(i).\n*\n* The contents of A are illustrated by the following example, with\n* n = 7, ilo = 2 and ihi = 6:\n*\n* on entry, on exit,\n*\n* ( a a a a a a a ) ( a a h h h h a )\n* ( a a a a a a ) ( a h h h h a )\n* ( a a a a a a ) ( h h h h h h )\n* ( a a a a a a ) ( v2 h h h h h )\n* ( a a a a a a ) ( v2 v3 h h h h )\n* ( a a a a a a ) ( v2 v3 v4 h h h )\n* ( a ) ( a )\n*\n* where a denotes an element of the original matrix A, h denotes a\n* modified element of the upper Hessenberg matrix H, and vi denotes an\n* element of the vector defining H(i).\n*\n* This file is a slight modification of LAPACK-3.0's DGEHRD\n* subroutine incorporating improvements proposed by Quintana-Orti and\n* Van de Geijn (2006). (See DLAHR2.)\n*\n* =====================================================================\n*\n\n");
return Qnil;
}
if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
printf("%s\n", "USAGE:\n tau, work, info, a = NumRu::Lapack.sgehrd( ilo, ihi, a, [:lwork => lwork, :usage => usage, :help => help])\n");
return Qnil;
}
} else
rblapack_options = Qnil;
if (argc != 3 && argc != 4)
rb_raise(rb_eArgError,"wrong number of arguments (%d for 3)", argc);
rblapack_ilo = argv[0];
rblapack_ihi = argv[1];
rblapack_a = argv[2];
if (argc == 4) {
rblapack_lwork = argv[3];
} else if (rblapack_options != Qnil) {
rblapack_lwork = rb_hash_aref(rblapack_options, ID2SYM(rb_intern("lwork")));
} else {
rblapack_lwork = Qnil;
}
ilo = NUM2INT(rblapack_ilo);
if (!NA_IsNArray(rblapack_a))
rb_raise(rb_eArgError, "a (3th argument) must be NArray");
if (NA_RANK(rblapack_a) != 2)
rb_raise(rb_eArgError, "rank of a (3th argument) must be %d", 2);
lda = NA_SHAPE0(rblapack_a);
n = NA_SHAPE1(rblapack_a);
if (NA_TYPE(rblapack_a) != NA_SFLOAT)
rblapack_a = na_change_type(rblapack_a, NA_SFLOAT);
a = NA_PTR_TYPE(rblapack_a, real*);
ihi = NUM2INT(rblapack_ihi);
if (rblapack_lwork == Qnil)
lwork = n;
else {
lwork = NUM2INT(rblapack_lwork);
}
{
na_shape_t shape[1];
shape[0] = n-1;
rblapack_tau = na_make_object(NA_SFLOAT, 1, shape, cNArray);
}
tau = NA_PTR_TYPE(rblapack_tau, real*);
{
na_shape_t shape[1];
shape[0] = MAX(1,lwork);
rblapack_work = na_make_object(NA_SFLOAT, 1, shape, cNArray);
}
work = NA_PTR_TYPE(rblapack_work, real*);
{
na_shape_t shape[2];
shape[0] = lda;
shape[1] = n;
rblapack_a_out__ = na_make_object(NA_SFLOAT, 2, shape, cNArray);
}
a_out__ = NA_PTR_TYPE(rblapack_a_out__, real*);
MEMCPY(a_out__, a, real, NA_TOTAL(rblapack_a));
rblapack_a = rblapack_a_out__;
a = a_out__;
sgehrd_(&n, &ilo, &ihi, a, &lda, tau, work, &lwork, &info);
rblapack_info = INT2NUM(info);
return rb_ary_new3(4, rblapack_tau, rblapack_work, rblapack_info, rblapack_a);
}
void
init_lapack_sgehrd(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
sHelp = sH;
sUsage = sU;
rblapack_ZERO = zero;
rb_define_module_function(mLapack, "sgehrd", rblapack_sgehrd, -1);
}
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