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#include "rb_lapack.h"
extern VOID slae2_(real* a, real* b, real* c, real* rt1, real* rt2);
static VALUE
rblapack_slae2(int argc, VALUE *argv, VALUE self){
VALUE rblapack_a;
real a;
VALUE rblapack_b;
real b;
VALUE rblapack_c;
real c;
VALUE rblapack_rt1;
real rt1;
VALUE rblapack_rt2;
real rt2;
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 rt1, rt2 = NumRu::Lapack.slae2( a, b, c, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n SUBROUTINE SLAE2( A, B, C, RT1, RT2 )\n\n* Purpose\n* =======\n*\n* SLAE2 computes the eigenvalues of a 2-by-2 symmetric matrix\n* [ A B ]\n* [ B C ].\n* On return, RT1 is the eigenvalue of larger absolute value, and RT2\n* is the eigenvalue of smaller absolute value.\n*\n\n* Arguments\n* =========\n*\n* A (input) REAL\n* The (1,1) element of the 2-by-2 matrix.\n*\n* B (input) REAL\n* The (1,2) and (2,1) elements of the 2-by-2 matrix.\n*\n* C (input) REAL\n* The (2,2) element of the 2-by-2 matrix.\n*\n* RT1 (output) REAL\n* The eigenvalue of larger absolute value.\n*\n* RT2 (output) REAL\n* The eigenvalue of smaller absolute value.\n*\n\n* Further Details\n* ===============\n*\n* RT1 is accurate to a few ulps barring over/underflow.\n*\n* RT2 may be inaccurate if there is massive cancellation in the\n* determinant A*C-B*B; higher precision or correctly rounded or\n* correctly truncated arithmetic would be needed to compute RT2\n* accurately in all cases.\n*\n* Overflow is possible only if RT1 is within a factor of 5 of overflow.\n* Underflow is harmless if the input data is 0 or exceeds\n* underflow_threshold / macheps.\n*\n* =====================================================================\n*\n\n");
return Qnil;
}
if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
printf("%s\n", "USAGE:\n rt1, rt2 = NumRu::Lapack.slae2( a, b, c, [: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_c = argv[2];
if (argc == 3) {
} else if (rblapack_options != Qnil) {
} else {
}
a = (real)NUM2DBL(rblapack_a);
c = (real)NUM2DBL(rblapack_c);
b = (real)NUM2DBL(rblapack_b);
slae2_(&a, &b, &c, &rt1, &rt2);
rblapack_rt1 = rb_float_new((double)rt1);
rblapack_rt2 = rb_float_new((double)rt2);
return rb_ary_new3(2, rblapack_rt1, rblapack_rt2);
}
void
init_lapack_slae2(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
sHelp = sH;
sUsage = sU;
rblapack_ZERO = zero;
rb_define_module_function(mLapack, "slae2", rblapack_slae2, -1);
}
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