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#include "rb_lapack.h"
extern VOID dlas2_(doublereal* f, doublereal* g, doublereal* h, doublereal* ssmin, doublereal* ssmax);
static VALUE
rblapack_dlas2(int argc, VALUE *argv, VALUE self){
VALUE rblapack_f;
doublereal f;
VALUE rblapack_g;
doublereal g;
VALUE rblapack_h;
doublereal h;
VALUE rblapack_ssmin;
doublereal ssmin;
VALUE rblapack_ssmax;
doublereal ssmax;
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 ssmin, ssmax = NumRu::Lapack.dlas2( f, g, h, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n SUBROUTINE DLAS2( F, G, H, SSMIN, SSMAX )\n\n* Purpose\n* =======\n*\n* DLAS2 computes the singular values of the 2-by-2 matrix\n* [ F G ]\n* [ 0 H ].\n* On return, SSMIN is the smaller singular value and SSMAX is the\n* larger singular value.\n*\n\n* Arguments\n* =========\n*\n* F (input) DOUBLE PRECISION\n* The (1,1) element of the 2-by-2 matrix.\n*\n* G (input) DOUBLE PRECISION\n* The (1,2) element of the 2-by-2 matrix.\n*\n* H (input) DOUBLE PRECISION\n* The (2,2) element of the 2-by-2 matrix.\n*\n* SSMIN (output) DOUBLE PRECISION\n* The smaller singular value.\n*\n* SSMAX (output) DOUBLE PRECISION\n* The larger singular value.\n*\n\n* Further Details\n* ===============\n*\n* Barring over/underflow, all output quantities are correct to within\n* a few units in the last place (ulps), even in the absence of a guard\n* digit in addition/subtraction.\n*\n* In IEEE arithmetic, the code works correctly if one matrix element is\n* infinite.\n*\n* Overflow will not occur unless the largest singular value itself\n* overflows, or is within a few ulps of overflow. (On machines with\n* partial overflow, like the Cray, overflow may occur if the largest\n* singular value is within a factor of 2 of overflow.)\n*\n* Underflow is harmless if underflow is gradual. Otherwise, results\n* may correspond to a matrix modified by perturbations of size near\n* the underflow threshold.\n*\n* ====================================================================\n*\n\n");
return Qnil;
}
if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
printf("%s\n", "USAGE:\n ssmin, ssmax = NumRu::Lapack.dlas2( f, g, h, [:usage => usage, :help => help])\n");
return Qnil;
}
} else
rblapack_options = Qnil;
if (argc != 3 && argc != 3)
rb_raise(rb_eArgError,"wrong number of arguments (%d for 3)", argc);
rblapack_f = argv[0];
rblapack_g = argv[1];
rblapack_h = argv[2];
if (argc == 3) {
} else if (rblapack_options != Qnil) {
} else {
}
f = NUM2DBL(rblapack_f);
h = NUM2DBL(rblapack_h);
g = NUM2DBL(rblapack_g);
dlas2_(&f, &g, &h, &ssmin, &ssmax);
rblapack_ssmin = rb_float_new((double)ssmin);
rblapack_ssmax = rb_float_new((double)ssmax);
return rb_ary_new3(2, rblapack_ssmin, rblapack_ssmax);
}
void
init_lapack_dlas2(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
sHelp = sH;
sUsage = sU;
rblapack_ZERO = zero;
rb_define_module_function(mLapack, "dlas2", rblapack_dlas2, -1);
}
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