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#include "rb_lapack.h"
extern VOID dlag2_(doublereal* a, integer* lda, doublereal* b, integer* ldb, doublereal* safmin, doublereal* scale1, doublereal* scale2, doublereal* wr1, doublereal* wr2, doublereal* wi);
static VALUE
rblapack_dlag2(int argc, VALUE *argv, VALUE self){
VALUE rblapack_a;
doublereal *a;
VALUE rblapack_b;
doublereal *b;
VALUE rblapack_safmin;
doublereal safmin;
VALUE rblapack_scale1;
doublereal scale1;
VALUE rblapack_scale2;
doublereal scale2;
VALUE rblapack_wr1;
doublereal wr1;
VALUE rblapack_wr2;
doublereal wr2;
VALUE rblapack_wi;
doublereal wi;
integer lda;
integer ldb;
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 scale1, scale2, wr1, wr2, wi = NumRu::Lapack.dlag2( a, b, safmin, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n SUBROUTINE DLAG2( A, LDA, B, LDB, SAFMIN, SCALE1, SCALE2, WR1, WR2, WI )\n\n* Purpose\n* =======\n*\n* DLAG2 computes the eigenvalues of a 2 x 2 generalized eigenvalue\n* problem A - w B, with scaling as necessary to avoid over-/underflow.\n*\n* The scaling factor \"s\" results in a modified eigenvalue equation\n*\n* s A - w B\n*\n* where s is a non-negative scaling factor chosen so that w, w B,\n* and s A do not overflow and, if possible, do not underflow, either.\n*\n\n* Arguments\n* =========\n*\n* A (input) DOUBLE PRECISION array, dimension (LDA, 2)\n* On entry, the 2 x 2 matrix A. It is assumed that its 1-norm\n* is less than 1/SAFMIN. Entries less than\n* sqrt(SAFMIN)*norm(A) are subject to being treated as zero.\n*\n* LDA (input) INTEGER\n* The leading dimension of the array A. LDA >= 2.\n*\n* B (input) DOUBLE PRECISION array, dimension (LDB, 2)\n* On entry, the 2 x 2 upper triangular matrix B. It is\n* assumed that the one-norm of B is less than 1/SAFMIN. The\n* diagonals should be at least sqrt(SAFMIN) times the largest\n* element of B (in absolute value); if a diagonal is smaller\n* than that, then +/- sqrt(SAFMIN) will be used instead of\n* that diagonal.\n*\n* LDB (input) INTEGER\n* The leading dimension of the array B. LDB >= 2.\n*\n* SAFMIN (input) DOUBLE PRECISION\n* The smallest positive number s.t. 1/SAFMIN does not\n* overflow. (This should always be DLAMCH('S') -- it is an\n* argument in order to avoid having to call DLAMCH frequently.)\n*\n* SCALE1 (output) DOUBLE PRECISION\n* A scaling factor used to avoid over-/underflow in the\n* eigenvalue equation which defines the first eigenvalue. If\n* the eigenvalues are complex, then the eigenvalues are\n* ( WR1 +/- WI i ) / SCALE1 (which may lie outside the\n* exponent range of the machine), SCALE1=SCALE2, and SCALE1\n* will always be positive. If the eigenvalues are real, then\n* the first (real) eigenvalue is WR1 / SCALE1 , but this may\n* overflow or underflow, and in fact, SCALE1 may be zero or\n* less than the underflow threshold if the exact eigenvalue\n* is sufficiently large.\n*\n* SCALE2 (output) DOUBLE PRECISION\n* A scaling factor used to avoid over-/underflow in the\n* eigenvalue equation which defines the second eigenvalue. If\n* the eigenvalues are complex, then SCALE2=SCALE1. If the\n* eigenvalues are real, then the second (real) eigenvalue is\n* WR2 / SCALE2 , but this may overflow or underflow, and in\n* fact, SCALE2 may be zero or less than the underflow\n* threshold if the exact eigenvalue is sufficiently large.\n*\n* WR1 (output) DOUBLE PRECISION\n* If the eigenvalue is real, then WR1 is SCALE1 times the\n* eigenvalue closest to the (2,2) element of A B**(-1). If the\n* eigenvalue is complex, then WR1=WR2 is SCALE1 times the real\n* part of the eigenvalues.\n*\n* WR2 (output) DOUBLE PRECISION\n* If the eigenvalue is real, then WR2 is SCALE2 times the\n* other eigenvalue. If the eigenvalue is complex, then\n* WR1=WR2 is SCALE1 times the real part of the eigenvalues.\n*\n* WI (output) DOUBLE PRECISION\n* If the eigenvalue is real, then WI is zero. If the\n* eigenvalue is complex, then WI is SCALE1 times the imaginary\n* part of the eigenvalues. WI will always be non-negative.\n*\n\n* =====================================================================\n*\n\n");
return Qnil;
}
if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
printf("%s\n", "USAGE:\n scale1, scale2, wr1, wr2, wi = NumRu::Lapack.dlag2( a, b, safmin, [: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_a = argv[0];
rblapack_b = argv[1];
rblapack_safmin = argv[2];
if (argc == 3) {
} else if (rblapack_options != Qnil) {
} else {
}
if (!NA_IsNArray(rblapack_a))
rb_raise(rb_eArgError, "a (1th argument) must be NArray");
if (NA_RANK(rblapack_a) != 2)
rb_raise(rb_eArgError, "rank of a (1th argument) must be %d", 2);
lda = NA_SHAPE0(rblapack_a);
if (NA_SHAPE1(rblapack_a) != (2))
rb_raise(rb_eRuntimeError, "shape 1 of a must be %d", 2);
if (NA_TYPE(rblapack_a) != NA_DFLOAT)
rblapack_a = na_change_type(rblapack_a, NA_DFLOAT);
a = NA_PTR_TYPE(rblapack_a, doublereal*);
safmin = NUM2DBL(rblapack_safmin);
if (!NA_IsNArray(rblapack_b))
rb_raise(rb_eArgError, "b (2th argument) must be NArray");
if (NA_RANK(rblapack_b) != 2)
rb_raise(rb_eArgError, "rank of b (2th argument) must be %d", 2);
ldb = NA_SHAPE0(rblapack_b);
if (NA_SHAPE1(rblapack_b) != (2))
rb_raise(rb_eRuntimeError, "shape 1 of b must be %d", 2);
if (NA_TYPE(rblapack_b) != NA_DFLOAT)
rblapack_b = na_change_type(rblapack_b, NA_DFLOAT);
b = NA_PTR_TYPE(rblapack_b, doublereal*);
dlag2_(a, &lda, b, &ldb, &safmin, &scale1, &scale2, &wr1, &wr2, &wi);
rblapack_scale1 = rb_float_new((double)scale1);
rblapack_scale2 = rb_float_new((double)scale2);
rblapack_wr1 = rb_float_new((double)wr1);
rblapack_wr2 = rb_float_new((double)wr2);
rblapack_wi = rb_float_new((double)wi);
return rb_ary_new3(5, rblapack_scale1, rblapack_scale2, rblapack_wr1, rblapack_wr2, rblapack_wi);
}
void
init_lapack_dlag2(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
sHelp = sH;
sUsage = sU;
rblapack_ZERO = zero;
rb_define_module_function(mLapack, "dlag2", rblapack_dlag2, -1);
}
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