void test_field1(flint_rand_t state)
{
/* tests in QQ[sqrt(5)] */
int iter;
fmpq_t k;
fmpq_poly_t p;
arb_t emb;
renf_t nf;
renf_elem_t a;
fmpq_poly_init(p);
fmpq_poly_set_coeff_si(p, 2, 1);
fmpq_poly_set_coeff_si(p, 1, -1);
fmpq_poly_set_coeff_si(p, 0, -1);
arb_init(emb);
arb_set_d(emb, 1.61803398874989);
arb_add_error_2exp_si(emb, -20);
renf_init(nf, p, emb, 20 + n_randint(state, 20));
arb_clear(emb);
renf_elem_init(a, nf);
fmpq_init(k);
/* (1+sqrt(5))/2 vs Fibonacci */
fmpq_poly_zero(p);
fmpq_poly_set_coeff_si(p, 1, -1);
for (iter = 1; iter < 50; iter++)
{
fprintf(stderr, "start iter = %d\n", iter);
fflush(stderr);
fmpz_fib_ui(fmpq_numref(k), iter+1);
fmpz_fib_ui(fmpq_denref(k), iter);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 1 - iter % 2, "sqrt(5)");
fprintf(stderr, "end\n");
fflush(stderr);
}
renf_elem_clear(a, nf);
renf_clear(nf);
fmpq_clear(k);
fmpq_poly_clear(p);
}
void test_field2(flint_rand_t state)
{
/* test in QQ[3^(1/4)] */
renf_t nf;
renf_elem_t a;
fmpq_t d, k;
fmpq_poly_t p;
fmpq_init(d);
fmpq_poly_init(p);
fmpq_set_si(d, 3, 1);
renf_init_nth_root_fmpq(nf, d, 4, 10 + n_randint(state, 10));
fmpq_clear(d);
fmpq_init(k);
renf_elem_init(a, nf);
/* test rationals */
/* --> 3^(1/4) */
fmpq_poly_set_coeff_si(p, 1, 1);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 2, "3^(1/4)");
/* --> 3^(1/4) - p_34 / q_34 */
/* ceil = 1 */
fmpz_set_str(fmpq_numref(k), "3871793620206447926", 10);
fmpz_set_str(fmpq_denref(k), "2941926960111028069", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 1, "3^(1/4)");
/* --> 3^(1/4) - p_35 / q_35 */
/* ceil = 0 */
fmpz_set_str(fmpq_numref(k), "4393442218385055959", 10);
fmpz_set_str(fmpq_denref(k), "3338294180377262795", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 0, "3^(1/4)");
/* --> 3^(1/4) - p_200 / q_200 */
fmpz_set_str(fmpq_numref(k), "51566086581654990699052199424489069476470199719930170996263916596162993841059250500042162091", 10);
fmpz_set_str(fmpq_denref(k), "39181752754141206003124111890355840072199542360218864430892618765033598468868752146602163065", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 1, "3^(1/4)");
/* --> 3^(1/4) - p_201 / q_201 */
fmpz_set_str(fmpq_numref(k), "80796322887694335717970676356641716096406222234122724217891106756946083353628876437327250032", 10);
fmpz_set_str(fmpq_denref(k), "61391929399498685496270115285641595325756438975454257165479021482386018841773493669624721869", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 0, "3^(1/4)");
/* */
fmpz_set_str(fmpq_numref(k), "13231942875843754343234", 10);
fmpz_set_str(fmpq_denref(k), "14321431341231112121", 10);
fmpq_poly_set_coeff_fmpq(p, 3, k);
fmpz_set_str(fmpq_numref(k), "148589873455543948591", 10);
fmpz_set_str(fmpq_denref(k), "12332111221111", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 2, k);
fmpz_set_str(fmpq_numref(k), "1233321469998711012392391", 10);
fmpz_set_str(fmpq_denref(k), "11814121556810191", 10);
fmpq_poly_set_coeff_fmpq(p, 1, k);
fmpz_set_str(fmpq_numref(k), "1249152314425433983202991363672458443993964487436329478959287771807457205881969983777233465754608376177969464841", 10);
fmpz_set_str(fmpq_denref(k), "10720278662399817731713810382544982753044312944075797382817281426908463944866446042500978893159281330135", 10);
fmpq_neg(k, k);
fmpq_poly_set_coeff_fmpq(p, 0, k);
renf_elem_set_fmpq_poly(a, p, nf);
check_ceil(a, nf, 231, "3^(1/4)");
renf_elem_clear(a, nf);
renf_clear(nf);
fmpq_clear(k);
fmpq_poly_clear(p);
}
int main()
{
slong iter;
FLINT_TEST_INIT(state);
{
ulong k;
arb_t a,b;
arf_t c,d;
fmpq_poly_t p;
arb_init(a);
arb_init(b);
arf_init(c);
arf_init(d);
/* x+1 */
fmpq_poly_init(p);
fmpq_poly_set_coeff_si(p, 0, 1);
fmpq_poly_set_coeff_si(p, 1, 1);
for (iter = 0; iter < 5000; iter++)
{
k = n_randint(state, 10000);
arb_set_si(a, k);
fmpq_poly_evaluate_arb(b, p, a, 30 + n_randint(state, 100));
if (!arb_equal_si(b, k + 1))
{
printf("FAIL (fmpq_poly_evaluate_arb):\n");
printf("a = "); arb_print(a); printf("\n");
printf("b = "); arb_print(b); printf("\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
abort();
}
arf_set_si(c, k);
fmpq_poly_evaluate_arf(d, p, c, 30 + n_randint(state, 100));
if (!arf_equal_si(d, k + 1))
{
printf("FAIL (fmpq_poly_evaluate_arf):\n");
printf("c = "); arf_print(c); printf("\n");
printf("d = "); arf_print(d); printf("\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
abort();
}
}
/* x^2 */
fmpq_poly_zero(p);
fmpq_poly_set_coeff_si(p, 2, 1);
for (iter = 0; iter < 1000; iter++)
{
k = n_randint(state, 10000);
arb_set_si(a, k);
fmpq_poly_evaluate_arb(b, p, a, 30 + n_randint(state, 100));
if (!arb_equal_si(b, k * k))
{
printf("Error (test_fmpq_poly_evaluate_arb):\n");
printf("a = "); arb_print(a); printf("\n");
printf("b = "); arb_print(b); printf("\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
abort();
}
arf_set_si(c, k);
fmpq_poly_evaluate_arf(d, p, c, 30 + n_randint(state, 100));
if (!arf_equal_si(d, k * k))
{
printf("Error (test_fmpq_poly_evaluate_arf):\n");
printf("c = "); arf_print(c); printf("\n");
printf("d = "); arf_print(d); printf("\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
abort();
}
}
fmpq_poly_clear(p);
arb_clear(a);
arb_clear(b);
arf_clear(c);
arf_clear(d);
}
/* check evaluate_arb agains exact evaluate_fmpq */
for (iter = 0; iter < 1000; iter++)
{
fmpq_poly_t p;
fmpq_t x,y;
arb_t a,b;
fmpq_poly_init(p);
fmpq_init(x);
fmpq_init(y);
arb_init(a);
arb_init(b);
fmpq_poly_randtest(p, state, 1 + n_randint(state,100), 10);
fmpq_randtest(x, state, 10);
arb_set_fmpq(a, x, 64);
fmpq_poly_evaluate_fmpq(y, p, x);
fmpq_poly_evaluate_arb(b, p, a, 60);
if (!arb_contains_fmpq(b, y))
{
printf("FAIL (y not in b):\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
printf("x = "); fmpq_print(x); printf("\n");
printf("y = "); fmpq_print(y); printf("\n");
printf("a = "); arb_print(a); printf("\n");
printf("b = "); arb_print(b); printf("\n");
abort();
}
fmpq_poly_evaluate_arb(a, p, a, 60);
if (!arb_equal(a,b))
{
printf("FAIL (a not equal b):\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
printf("x = "); fmpq_print(x); printf("\n");
printf("y = "); fmpq_print(y); printf("\n");
printf("a = "); arb_print(a); printf("\n");
printf("b = "); arb_print(b); printf("\n");
abort();
}
fmpq_poly_clear(p);
fmpq_clear(x);
fmpq_clear(y);
arb_clear(a);
arb_clear(b);
}
/* test aliasing */
for (iter = 0; iter < 1000; iter++)
{
fmpq_poly_t p;
arb_t a,b;
arf_t c,d;
fmpq_poly_init(p);
arb_init(a);
arb_init(b);
arf_init(c);
arf_init(d);
fmpq_poly_randtest(p, state, 1 + n_randint(state,100), 10);
arb_randtest(a, state, 60, 10);
arb_randtest(b, state, 60, 10);
arf_randtest(c, state, 60, 10);
arf_randtest(d, state, 60, 10);
fmpq_poly_evaluate_arb(b, p, a, 60);
fmpq_poly_evaluate_arb(a, p, a, 60);
if (!arb_equal(a, b))
{
printf("FAIL (a not equal b):\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
printf("a = "); arb_print(a); printf("\n");
printf("b = "); arb_print(b); printf("\n");
abort();
}
fmpq_poly_evaluate_arf(d, p, c, 60);
fmpq_poly_evaluate_arf(c, p, c, 60);
if (!arf_equal(c, d))
{
printf("FAIL (c not equal d):\n");
printf("p = "); fmpq_poly_print(p); printf("\n");
printf("c = "); arf_print(c); printf("\n");
printf("d = "); arf_print(d); printf("\n");
}
fmpq_poly_clear(p);
arb_clear(a);
arb_clear(b);
arf_clear(c);
arf_clear(d);
}
FLINT_TEST_CLEANUP(state);
return 0;
}
int main(int argc, char *argv[])
{
fmpz_poly_t f, g;
fmpz_poly_factor_t fac;
fmpz_t t;
slong compd, printd, i, j;
if (argc < 2)
{
flint_printf("poly_roots [-refine d] [-print d] <poly>\n\n");
flint_printf("Isolates all the complex roots of a polynomial with integer coefficients.\n\n");
flint_printf("If -refine d is passed, the roots are refined to an absolute tolerance\n");
flint_printf("better than 10^(-d). By default, the roots are only computed to sufficient\n");
flint_printf("accuracy to isolate them. The refinement is not currently done efficiently.\n\n");
flint_printf("If -print d is passed, the computed roots are printed to d decimals.\n");
flint_printf("By default, the roots are not printed.\n\n");
flint_printf("The polynomial can be specified by passing the following as <poly>:\n\n");
flint_printf("a <n> Easy polynomial 1 + 2x + ... + (n+1)x^n\n");
flint_printf("t <n> Chebyshev polynomial T_n\n");
flint_printf("u <n> Chebyshev polynomial U_n\n");
flint_printf("p <n> Legendre polynomial P_n\n");
flint_printf("c <n> Cyclotomic polynomial Phi_n\n");
flint_printf("s <n> Swinnerton-Dyer polynomial S_n\n");
flint_printf("b <n> Bernoulli polynomial B_n\n");
flint_printf("w <n> Wilkinson polynomial W_n\n");
flint_printf("e <n> Taylor series of exp(x) truncated to degree n\n");
flint_printf("m <n> <m> The Mignotte-like polynomial x^n + (100x+1)^m, n > m\n");
flint_printf("coeffs <c0 c1 ... cn> c0 + c1 x + ... + cn x^n\n\n");
flint_printf("Concatenate to multiply polynomials, e.g.: p 5 t 6 coeffs 1 2 3\n");
flint_printf("for P_5(x)*T_6(x)*(1+2x+3x^2)\n\n");
return 1;
}
compd = 0;
printd = 0;
fmpz_poly_init(f);
fmpz_poly_init(g);
fmpz_init(t);
fmpz_poly_one(f);
for (i = 1; i < argc; i++)
{
if (!strcmp(argv[i], "-refine"))
{
compd = atol(argv[i+1]);
i++;
}
else if (!strcmp(argv[i], "-print"))
{
printd = atol(argv[i+1]);
i++;
}
else if (!strcmp(argv[i], "a"))
{
slong n = atol(argv[i+1]);
fmpz_poly_zero(g);
for (j = 0; j <= n; j++)
fmpz_poly_set_coeff_ui(g, j, j+1);
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "t"))
{
arith_chebyshev_t_polynomial(g, atol(argv[i+1]));
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "u"))
{
arith_chebyshev_u_polynomial(g, atol(argv[i+1]));
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "p"))
{
fmpq_poly_t h;
fmpq_poly_init(h);
arith_legendre_polynomial(h, atol(argv[i+1]));
fmpq_poly_get_numerator(g, h);
fmpz_poly_mul(f, f, g);
fmpq_poly_clear(h);
i++;
}
else if (!strcmp(argv[i], "c"))
{
arith_cyclotomic_polynomial(g, atol(argv[i+1]));
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "s"))
{
arith_swinnerton_dyer_polynomial(g, atol(argv[i+1]));
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "b"))
{
fmpq_poly_t h;
fmpq_poly_init(h);
arith_bernoulli_polynomial(h, atol(argv[i+1]));
fmpq_poly_get_numerator(g, h);
fmpz_poly_mul(f, f, g);
fmpq_poly_clear(h);
i++;
}
else if (!strcmp(argv[i], "w"))
{
slong n = atol(argv[i+1]);
fmpz_poly_zero(g);
fmpz_poly_fit_length(g, n+2);
arith_stirling_number_1_vec(g->coeffs, n+1, n+2);
_fmpz_poly_set_length(g, n+2);
fmpz_poly_shift_right(g, g, 1);
fmpz_poly_mul(f, f, g);
i++;
}
else if (!strcmp(argv[i], "e"))
{
fmpq_poly_t h;
fmpq_poly_init(h);
fmpq_poly_set_coeff_si(h, 0, 0);
fmpq_poly_set_coeff_si(h, 1, 1);
fmpq_poly_exp_series(h, h, atol(argv[i+1]) + 1);
fmpq_poly_get_numerator(g, h);
fmpz_poly_mul(f, f, g);
fmpq_poly_clear(h);
i++;
}
else if (!strcmp(argv[i], "m"))
{
fmpz_poly_zero(g);
fmpz_poly_set_coeff_ui(g, 0, 1);
fmpz_poly_set_coeff_ui(g, 1, 100);
fmpz_poly_pow(g, g, atol(argv[i+2]));
fmpz_poly_set_coeff_ui(g, atol(argv[i+1]), 1);
fmpz_poly_mul(f, f, g);
i += 2;
}
else if (!strcmp(argv[i], "coeffs"))
{
fmpz_poly_zero(g);
i++;
j = 0;
while (i < argc)
{
if (fmpz_set_str(t, argv[i], 10) != 0)
{
i--;
break;
}
fmpz_poly_set_coeff_fmpz(g, j, t);
i++;
j++;
}
fmpz_poly_mul(f, f, g);
}
}
fmpz_poly_factor_init(fac);
flint_printf("computing squarefree factorization...\n");
TIMEIT_ONCE_START
fmpz_poly_factor_squarefree(fac, f);
TIMEIT_ONCE_STOP
TIMEIT_ONCE_START
for (i = 0; i < fac->num; i++)
{
flint_printf("roots with multiplicity %wd\n", fac->exp[i]);
fmpz_poly_complex_roots_squarefree(fac->p + i,
32, compd * 3.32193 + 2, printd);
}
TIMEIT_ONCE_STOP
fmpz_poly_factor_clear(fac);
fmpz_poly_clear(f);
fmpz_poly_clear(g);
fmpz_clear(t);
flint_cleanup();
return EXIT_SUCCESS;
}
int fmpq_poly_oz_sqrt_approx_pade(fmpq_poly_t f_sqrt, const fmpq_poly_t f, const long n, const int p, const mpfr_prec_t prec, const mpfr_prec_t bound, oz_flag_t flags, const fmpq_poly_t init) {
fmpq_poly_t y; fmpq_poly_init(y);
fmpq_poly_t y_next; fmpq_poly_init(y_next);
fmpq_poly_t z; fmpq_poly_init(z);
fmpq_poly_t z_next; fmpq_poly_init(z_next);
mpfr_t norm; mpfr_init2(norm, prec);
mpfr_t prev_norm; mpfr_init2(prev_norm, prec);
mpfr_t log_f; mpfr_init2(log_f, prec);
if (init) {
// z = y/x
fmpq_poly_set(y, init);
_fmpq_poly_oz_invert_approx(z, f, n, prec);
fmpq_poly_oz_mul(z, z, y, n);
} else {
fmpq_poly_set(y, f);
fmpq_poly_set_coeff_si(z, 0, 1);
}
fmpq_t *xi = (fmpq_t*)calloc(p, sizeof(fmpq_t));
fmpq_t *a2 = (fmpq_t*)calloc(p, sizeof(fmpq_t));
fmpq_t *c = (fmpq_t*)calloc(p, sizeof(fmpq_t));
fmpq_poly_t *t_ = (fmpq_poly_t*)calloc(p, sizeof(fmpq_poly_t));
fmpq_poly_t *s_ = (fmpq_poly_t*)calloc(p, sizeof(fmpq_poly_t));
mpfr_t pi; mpfr_init2(pi, 4*prec);
mpfr_const_pi(pi, MPFR_RNDN);
#pragma omp parallel for
for(int i=0; i<p; i++) {
mpfr_t xi_r; mpfr_init2(xi_r, 4*prec);
mpfr_t a2_r; mpfr_init2(a2_r, 4*prec);
/* ζ_i = 1/2 * (1 + cos( (2·i -1)·π/(2·p) )) */
mpfr_set_si(xi_r, 2*i+1, MPFR_RNDN);
mpfr_mul(xi_r, xi_r, pi, MPFR_RNDN);
mpfr_div_si(xi_r, xi_r, 2*p, MPFR_RNDN);
mpfr_cos(xi_r, xi_r, MPFR_RNDN);
mpfr_add_si(xi_r, xi_r, 1, MPFR_RNDN);
mpfr_div_si(xi_r, xi_r, 2, MPFR_RNDN);
/* α_i^2 = 1/ζ_i -1 */
mpfr_set_si(a2_r, 1, MPFR_RNDN);
mpfr_div(a2_r, a2_r, xi_r, MPFR_RNDN);
mpfr_sub_si(a2_r, a2_r, 1, MPFR_RNDN);
fmpq_init(xi[i]);
fmpq_init(a2[i]);
fmpq_set_mpfr(xi[i], xi_r, MPFR_RNDN);
fmpq_set_mpfr(a2[i], a2_r, MPFR_RNDN);
fmpq_init(c[i]);
fmpq_poly_init(t_[i]);
fmpq_poly_init(s_[i]);
mpfr_clear(xi_r);
mpfr_clear(a2_r);
}
mpfr_clear(pi);
uint64_t t = oz_walltime(0);
int r = 0;
int cont = 1;
for(long k=0; cont; k++) {
if (k == 0 || mpfr_cmp_ui(prev_norm, 1) > 0)
_fmpq_poly_oz_sqrt_approx_scale(y, z, n, prec);
/* T = sum([1/xi[i] * ~(Z*Y + a2[i]) for i in range(p)]) */
#pragma omp parallel for
for(int i=0; i<p; i++) {
fmpq_poly_oz_mul(t_[i], z, y, n);
fmpq_poly_get_coeff_fmpq(c[i], t_[i], 0);
fmpq_add(c[i], c[i], a2[i]);
fmpq_poly_set_coeff_fmpq(t_[i], 0, c[i]);
fmpq_poly_scalar_mul_fmpq(t_[i], t_[i], xi[i]);
_fmpq_poly_oz_invert_approx(s_[i], t_[i], n, prec);
}
for(int i=1; i<p; i++)
fmpq_poly_add(s_[0], s_[0], s_[i]);
#pragma omp parallel sections
{
#pragma omp section
{
fmpq_poly_oz_mul(y_next, y, s_[0], n);
fmpq_poly_scalar_div_si(y_next, y_next, p);
fmpq_poly_set(y, y_next);
}
#pragma omp section
{
fmpq_poly_oz_mul(z_next, z, s_[0], n);
fmpq_poly_scalar_div_si(z_next, z_next, p);
fmpq_poly_set(z, z_next);
}
}
cont = !_fmpq_poly_oz_sqrt_approx_break(norm, y, f, n, bound, prec);
if(flags & OZ_VERBOSE) {
mpfr_log2(log_f, norm, MPFR_RNDN);
mpfr_fprintf(stderr, "Computing sqrt(Σ):: k: %4d, Δ=|sqrt(Σ)^2-Σ|: %7.2Rf", k, log_f);
fprintf(stderr, " <? %4ld, ", -bound);
fprintf(stderr, "t: %8.2fs\n", oz_seconds(oz_walltime(t)));
fflush(0);
}
if (cont) {
if (k>0 && mpfr_cmp_ui_2exp(norm, 1, bound) >= 0) {
/* something went really wrong */
r = -1;
break;
}
if (k>0 && mpfr_cmp(norm, prev_norm) >= 0) {
/* we don't converge any more */
r = 1;
break;
}
mpfr_set(prev_norm, norm, MPFR_RNDN);
}
}
for(int i=0; i<p; i++) {
fmpq_clear(xi[i]);
fmpq_clear(a2[i]);
fmpq_clear(c[i]);
fmpq_poly_clear(t_[i]);
fmpq_poly_clear(s_[i]);
}
free(xi);
free(a2);
free(c);
free(t_);
free(s_);
mpfr_clear(log_f);
fmpq_poly_set(f_sqrt, y);
mpfr_clear(norm);
mpfr_clear(prev_norm);
fmpq_poly_clear(y_next);
fmpq_poly_clear(y);
fmpq_poly_clear(z_next);
fmpq_poly_clear(z);
return r;
}
int fmpq_poly_oz_sqrt_approx_db(fmpq_poly_t f_sqrt, const fmpq_poly_t f, const long n, const mpfr_prec_t prec, const mpfr_prec_t bound, oz_flag_t flags, const fmpq_poly_t init) {
fmpq_poly_t y; fmpq_poly_init(y);
fmpq_poly_t y_next; fmpq_poly_init(y_next);
fmpq_poly_t z; fmpq_poly_init(z);
fmpq_poly_t z_next; fmpq_poly_init(z_next);
mpfr_t norm; mpfr_init2(norm, prec);
mpfr_t prev_norm; mpfr_init2(prev_norm, prec);
mpfr_t log_f; mpfr_init2(log_f, prec);
uint64_t t = oz_walltime(0);
if (init) {
// z = y/x
fmpq_poly_set(y, init);
_fmpq_poly_oz_invert_approx(z, f, n, prec);
fmpq_poly_oz_mul(z, z, y, n);
} else {
fmpq_poly_set(y, f);
fmpq_poly_set_coeff_si(z, 0, 1);
}
int r = 0;
for(long k=0; ; k++) {
if (k == 0 || mpfr_cmp_ui(prev_norm, 1) > 0)
_fmpq_poly_oz_sqrt_approx_scale(y, z, n, prec);
#pragma omp parallel sections
{
#pragma omp section
{
_fmpq_poly_oz_invert_approx(y_next, z, n, prec);
fmpq_poly_add(y_next, y_next, y);
fmpq_poly_scalar_div_si(y_next, y_next, 2);
flint_cleanup();
}
#pragma omp section
{
_fmpq_poly_oz_invert_approx(z_next, y, n, prec);
fmpq_poly_add(z_next, z_next, z);
fmpq_poly_scalar_div_si(z_next, z_next, 2);
flint_cleanup();
}
}
fmpq_poly_set(y, y_next);
fmpq_poly_set(z, z_next);
r = _fmpq_poly_oz_sqrt_approx_break(norm, y, f, n, bound, prec);
if(flags & OZ_VERBOSE) {
mpfr_log2(log_f, norm, MPFR_RNDN);
mpfr_fprintf(stderr, "Computing sqrt(Σ):: k: %4d, Δ=|sqrt(Σ)^2-Σ|: %7.2Rf", k, log_f);
fprintf(stderr, " <? %4ld, ", -bound);
fprintf(stderr, "t: %8.2fs\n", oz_seconds(oz_walltime(t)));
fflush(0);
}
if(r) {
r = 0;
break;
}
if (k>0 && mpfr_cmp_ui_2exp(norm, 1, bound) >= 0) {
/* something went really wrong */
r = -1;
break;
}
mpfr_div_ui(prev_norm, prev_norm, 2, MPFR_RNDN);
if (k>0 && mpfr_cmp(norm, prev_norm) >= 0) {
/* we don't converge any more */
r = 1;
break;
}
mpfr_set(prev_norm, norm, MPFR_RNDN);
}
mpfr_clear(log_f);
fmpq_poly_set(f_sqrt, y);
mpfr_clear(norm);
mpfr_clear(prev_norm);
fmpq_poly_clear(y_next);
fmpq_poly_clear(y);
fmpq_poly_clear(z_next);
fmpq_poly_clear(z);
return r;
}
