flint-sys 0.9.0

Bindings to the FLINT C library
Documentation 
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/*
  Copyright (C) 2018 Tommy Hofmann
                2020 Julian Rüth

 ******************************************************************************/

#include "test_helpers.h"
#include "fmpz_mod.h"
#include "fmpz_mod_poly.h"
#include "nf_elem.h"

TEST_FUNCTION_START(nf_elem_get_fmpz_mod_poly, state)
{
    int i, result;

    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        slong j;
        nf_t nf;
        nf_elem_t a;
        fmpz_mod_poly_t reduced_elem;
        fmpz_t coeff, mod, reduced_coeff;
        fmpz_mod_ctx_t ctx;

        fmpz_init(mod);
        fmpz_randtest_unsigned(mod, state, 2 * FLINT_BITS);
        fmpz_add_ui(mod, mod, 2);

        fmpz_init(coeff);
        fmpz_init(reduced_coeff);
        fmpz_mod_ctx_init(ctx, mod);
        fmpz_mod_poly_init(reduced_elem, ctx);

        nf_init_randtest(nf, state, 40, 200);

        nf_elem_init(a, nf);

        nf_elem_randtest(a, state, 200, nf);

        nf_elem_get_fmpz_mod_poly_den(reduced_elem, a, nf, 0, ctx);

        for (j = 0; j < fmpq_poly_degree(nf->pol); j++)
        {
            nf_elem_get_coeff_fmpz(coeff, a, j, nf);
            fmpz_mod(coeff, coeff, mod);
            fmpz_mod_poly_get_coeff_fmpz(reduced_coeff, reduced_elem, j, ctx);
            result = fmpz_equal(reduced_coeff, coeff);
            if (!result)
            {
                printf("FAIL: Reducing without denominator\n");
                printf("f = "); fmpq_poly_print_pretty(nf->pol, "x"); printf("\n");
                printf("a = "); nf_elem_print_pretty(a, nf, "x"); printf("\n");
                printf("n = "); fmpz_print(mod); printf("\n");
                printf("a mod n = ");
                fmpz_mod_poly_print_pretty(reduced_elem, "x", ctx);
                printf("\n");
                flint_abort();
            }
        }

        nf_elem_clear(a, nf);
        fmpz_mod_poly_clear(reduced_elem, ctx);
        fmpz_mod_ctx_clear(ctx);
        fmpz_clear(coeff);
        fmpz_clear(reduced_coeff);
        fmpz_clear(mod);
        nf_clear(nf);
    }

    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        slong j;
        nf_t nf;
        nf_elem_t a;
        fmpz_mod_poly_t reduced_elem;
        fmpz_t coeff, reduced_coeff, den, mod, d_mod, d_modinv;
        fmpz_mod_ctx_t ctx;

        fmpz_init(coeff);
        fmpz_init(den);
        fmpz_init(mod);
        fmpz_init(d_mod);
        fmpz_init(d_modinv);
        fmpz_init(reduced_coeff);

        fmpz_init(mod);
        fmpz_randtest_unsigned(mod, state, 2 * FLINT_BITS);
        fmpz_add_ui(mod, mod, 2);

        fmpz_mod_ctx_init(ctx, mod);
        fmpz_mod_poly_init(reduced_elem, ctx);

        nf_init_randtest(nf, state, 40, 200);

        nf_elem_init(a, nf);

        do {
            nf_elem_randtest(a, state, 200, nf);
            nf_elem_get_den(den, a, nf);
            fmpz_mod(d_mod, den, mod);
            fmpz_gcd(d_mod, d_mod, mod);
        } while (!fmpz_is_one(d_mod));

        nf_elem_get_fmpz_mod_poly(reduced_elem, a, nf, ctx);

        for (j = 0; j < fmpq_poly_degree(nf->pol); j++)
        {
            nf_elem_get_coeff_fmpz(coeff, a, j, nf);
            nf_elem_get_den(den, a, nf);
            fmpz_invmod(d_modinv, den, mod);
            fmpz_mul(coeff, coeff, d_modinv);
            fmpz_mod(coeff, coeff, mod);
            fmpz_mod_poly_get_coeff_fmpz(reduced_coeff, reduced_elem, j, ctx);
            result = (fmpz_equal(coeff, reduced_coeff));
            if (!result)
            {
                printf("FAIL: Reducing element with denominator\n");
                printf("a = "); nf_elem_print_pretty(a, nf, "x"); printf("\n");
                printf("n = "); fmpz_print(mod); flint_printf("\n");
                printf("a mod n = ");
                fmpz_mod_poly_print_pretty(reduced_elem, "x", ctx);
                printf("\n");
                flint_abort();
            }
        }

        fmpz_clear(den);
        fmpz_clear(mod);
        fmpz_clear(coeff);
        fmpz_clear(reduced_coeff);
        fmpz_clear(d_mod);
        fmpz_clear(d_modinv);
        nf_elem_clear(a, nf);
        fmpz_mod_poly_clear(reduced_elem, ctx);
        fmpz_mod_ctx_clear(ctx);
        nf_clear(nf);
    }

    TEST_FUNCTION_END(state);
}