Esempio n. 1
0
void qadic_trace(padic_t rop, const qadic_t op, const qadic_ctx_t ctx)
{
    const slong N = padic_prec(rop);

    if (qadic_is_zero(op) || op->val >= N)
    {
        padic_zero(rop);
    }
    else
    {
        fmpz_t pN;
        int alloc;

        alloc = _padic_ctx_pow_ui(pN, N - op->val, &ctx->pctx);

        _qadic_trace(padic_unit(rop), op->coeffs, op->length, 
                     ctx->a, ctx->j, ctx->len, pN);
        padic_val(rop) = op->val;

        _padic_canonicalise(rop, &ctx->pctx);

        if (alloc)
            fmpz_clear(pN);
    }
}
Esempio n. 2
0
void qadic_norm_resultant(padic_t rop, const qadic_t op, const qadic_ctx_t ctx)
{
    const slong N = padic_prec(rop);
    const slong d = qadic_ctx_degree(ctx);

    /* N(p^v u) = p^{dv} N(u) */

    if (qadic_is_zero(op) || d * op->val >= N)
    {
        padic_zero(rop);
    }
    else
    {
        _qadic_norm_resultant(padic_unit(rop), op->coeffs, op->length, 
                              ctx->a, ctx->j, ctx->len, (&ctx->pctx)->p, 
                              N - d * op->val);
        padic_val(rop) = d * op->val;
    }
}
Esempio n. 3
0
static
void fmpz_poly_evaluate_qadic(qadic_t rop,
                              const fmpz_poly_t op1, const qadic_t op2, const qadic_ctx_t ctx)
{
    const long N = qadic_prec(rop);
    const long d = qadic_ctx_degree(ctx);

    if (N <= 0 || op2->val != 0 || rop == op2)
    {
        printf("Exception (fmpz_poly_evaluate_qadic):\n");
        printf("Currently assumes that N > 0 and op2->val == 0, \n");
        printf("and does not support aliasing.\n");
        abort();
    }

    if (fmpz_poly_is_zero(op1))
    {
        qadic_zero(rop);
    }
    else if (qadic_is_zero(op2))
    {
        padic_poly_set_fmpz(rop, op1->coeffs + 0, &ctx->pctx);
    }
    else
    {
        fmpz_t pN;

        fmpz_init(pN);
        fmpz_pow_ui(pN, (&ctx->pctx)->p, N);

        padic_poly_fit_length(rop, d);
        _fmpz_mod_poly_compose_smod(rop->coeffs,
                                    op1->coeffs, op1->length, op2->coeffs, op2->length,
                                    ctx->a, ctx->j, ctx->len, pN);
        _padic_poly_set_length(rop, d);
        qadic_reduce(rop, ctx);

        fmpz_clear(pN);
    }
}
Esempio n. 4
0
void frob(const mpoly_t P, const ctx_t ctxFracQt,
          const qadic_t t1, const qadic_ctx_t Qq,
          prec_t *prec, const prec_t *prec_in,
          int verbose)
{
    const padic_ctx_struct *Qp = &Qq->pctx;
    const fmpz *p = Qp->p;
    const long a  = qadic_ctx_degree(Qq);
    const long n  = P->n - 1;
    const long d  = mpoly_degree(P, -1, ctxFracQt);
    const long b  = gmc_basis_size(n, d);

    long i, j, k;

    /* Diagonal fibre */
    padic_mat_t F0;

    /* Gauss--Manin Connection */
    mat_t M;
    mon_t *bR, *bC;
    fmpz_poly_t r;

    /* Local solution */
    fmpz_poly_mat_t C, Cinv;
    long vC, vCinv;

    /* Frobenius */
    fmpz_poly_mat_t F;
    long vF;

    fmpz_poly_mat_t F1;
    long vF1;

    fmpz_poly_t cp;

    clock_t c0, c1;
    double c;

    if (verbose)
    {
        printf("Input:\n");
        printf("  P  = "), mpoly_print(P, ctxFracQt), printf("\n");
        printf("  p  = "), fmpz_print(p), printf("\n");
        printf("  t1 = "), qadic_print_pretty(t1, Qq), printf("\n");
        printf("\n");
        fflush(stdout);
    }

    /* Step 1 {M, r} *********************************************************/

    c0 = clock();

    mat_init(M, b, b, ctxFracQt);
    fmpz_poly_init(r);

    gmc_compute(M, &bR, &bC, P, ctxFracQt);

    {
        fmpz_poly_t t;

        fmpz_poly_init(t);
        fmpz_poly_set_ui(r, 1);
        for (i = 0; i < M->m; i++)
            for (j = 0; j < M->n; j++)
            {
                fmpz_poly_lcm(t, r, fmpz_poly_q_denref(
                                  (fmpz_poly_q_struct *) mat_entry(M, i, j, ctxFracQt)));
                fmpz_poly_swap(r, t);
            }
        fmpz_poly_clear(t);
    }

    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;

    if (verbose)
    {
        printf("Gauss-Manin connection:\n");
        printf("  r(t) = "), fmpz_poly_print_pretty(r, "t"), printf("\n");
        printf("  Time = %f\n", c);
        printf("\n");
        fflush(stdout);
    }

    {
        qadic_t t;

        qadic_init2(t, 1);
        fmpz_poly_evaluate_qadic(t, r, t1, Qq);

        if (qadic_is_zero(t))
        {
            printf("Exception (deformation_frob).\n");
            printf("The resultant r evaluates to zero (mod p) at t1.\n");
            abort();
        }
        qadic_clear(t);
    }

    /* Precisions ************************************************************/

    if (prec_in != NULL)
    {
        *prec = *prec_in;
    }
    else
    {
        deformation_precisions(prec, p, a, n, d, fmpz_poly_degree(r));
    }

    if (verbose)
    {
        printf("Precisions:\n");
        printf("  N0   = %ld\n", prec->N0);
        printf("  N1   = %ld\n", prec->N1);
        printf("  N2   = %ld\n", prec->N2);
        printf("  N3   = %ld\n", prec->N3);
        printf("  N3i  = %ld\n", prec->N3i);
        printf("  N3w  = %ld\n", prec->N3w);
        printf("  N3iw = %ld\n", prec->N3iw);
        printf("  N4   = %ld\n", prec->N4);
        printf("  m    = %ld\n", prec->m);
        printf("  K    = %ld\n", prec->K);
        printf("  r    = %ld\n", prec->r);
        printf("  s    = %ld\n", prec->s);
        printf("\n");
        fflush(stdout);
    }

    /* Initialisation ********************************************************/

    padic_mat_init2(F0, b, b, prec->N4);

    fmpz_poly_mat_init(C, b, b);
    fmpz_poly_mat_init(Cinv, b, b);

    fmpz_poly_mat_init(F, b, b);
    vF = 0;

    fmpz_poly_mat_init(F1, b, b);
    vF1 = 0;

    fmpz_poly_init(cp);

    /* Step 2 {F0} ***********************************************************/

    {
        padic_ctx_t pctx_F0;
        fmpz *t;

        padic_ctx_init(pctx_F0, p, FLINT_MIN(prec->N4 - 10, 0), prec->N4, PADIC_VAL_UNIT);
        t = _fmpz_vec_init(n + 1);

        c0 = clock();

        mpoly_diagonal_fibre(t, P, ctxFracQt);

        diagfrob(F0, t, n, d, prec->N4, pctx_F0, 0);
        padic_mat_transpose(F0, F0);

        c1 = clock();
        c  = (double) (c1 - c0) / CLOCKS_PER_SEC;

        if (verbose)
        {
            printf("Diagonal fibre:\n");
            printf("  P(0) = {"), _fmpz_vec_print(t, n + 1), printf("}\n");
            printf("  Time = %f\n", c);
            printf("\n");
            fflush(stdout);
        }

        _fmpz_vec_clear(t, n + 1);
        padic_ctx_clear(pctx_F0);
    }

    /* Step 3 {C, Cinv} ******************************************************/
    /*
        Compute C as a matrix over Z_p[[t]].  A is the same but as a series
        of matrices over Z_p.  Mt is the matrix -M^t, and Cinv is C^{-1}^t,
        the local solution of the differential equation replacing M by Mt.
     */

    c0 = clock();
    {
        const long K = prec->K;
        padic_mat_struct *A;

        gmde_solve(&A, K, p, prec->N3, prec->N3w, M, ctxFracQt);
        gmde_convert_soln(C, &vC, A, K, p);

        for(i = 0; i < K; i++)
            padic_mat_clear(A + i);
        free(A);
    }
    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
    if (verbose)
    {
        printf("Local solution:\n");
        printf("  Time for C      = %f\n", c);
        fflush(stdout);
    }

    c0 = clock();
    {
        const long K = (prec->K + (*p) - 1) / (*p);
        mat_t Mt;
        padic_mat_struct *Ainv;

        mat_init(Mt, b, b, ctxFracQt);
        mat_transpose(Mt, M, ctxFracQt);
        mat_neg(Mt, Mt, ctxFracQt);
        gmde_solve(&Ainv, K, p, prec->N3i, prec->N3iw, Mt, ctxFracQt);
        gmde_convert_soln(Cinv, &vCinv, Ainv, K, p);

        fmpz_poly_mat_transpose(Cinv, Cinv);
        fmpz_poly_mat_compose_pow(Cinv, Cinv, *p);

        for(i = 0; i < K; i++)
            padic_mat_clear(Ainv + i);
        free(Ainv);
        mat_clear(Mt, ctxFracQt);
    }
    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
    if (verbose)
    {
        printf("  Time for C^{-1} = %f\n", c);
        printf("\n");
        fflush(stdout);
    }

    /* Step 4 {F(t) := C(t) F(0) C(t^p)^{-1}} ********************************/
    /*
        Computes the product C(t) F(0) C(t^p)^{-1} modulo (p^{N_2}, t^K).
        This is done by first computing the unit part of the product
        exactly over the integers modulo t^K.
     */

    c0 = clock();
    {
        fmpz_t pN;
        fmpz_poly_mat_t T;

        fmpz_init(pN);
        fmpz_poly_mat_init(T, b, b);

        for (i = 0; i < b; i++)
        {
            /* Find the unique k s.t. F0(i,k) is non-zero */
            for (k = 0; k < b; k++)
                if (!fmpz_is_zero(padic_mat_entry(F0, i, k)))
                    break;
            if (k == b)
            {
                printf("Exception (frob). F0 is singular.\n\n");
                abort();
            }

            for (j = 0; j < b; j++)
            {
                fmpz_poly_scalar_mul_fmpz(fmpz_poly_mat_entry(T, i, j),
                                          fmpz_poly_mat_entry(Cinv, k, j),
                                          padic_mat_entry(F0, i, k));
            }
        }

        fmpz_poly_mat_mul(F, C, T);
        fmpz_poly_mat_truncate(F, prec->K);
        vF = vC + padic_mat_val(F0) + vCinv;

        /* Canonicalise (F, vF) */
        {
            long v = fmpz_poly_mat_ord_p(F, p);

            if (v == LONG_MAX)
            {
                printf("ERROR (deformation_frob).  F(t) == 0.\n");
                abort();
            }
            else if (v > 0)
            {
                fmpz_pow_ui(pN, p, v);
                fmpz_poly_mat_scalar_divexact_fmpz(F, F, pN);
                vF = vF + v;
            }
        }

        /* Reduce (F, vF) modulo p^{N2} */
        fmpz_pow_ui(pN, p, prec->N2 - vF);
        fmpz_poly_mat_scalar_mod_fmpz(F, F, pN);

        fmpz_clear(pN);
        fmpz_poly_mat_clear(T);
    }
    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
    if (verbose)
    {
        printf("Matrix for F(t):\n");
        printf("  Time = %f\n", c);
        printf("\n");
        fflush(stdout);
    }

    /* Step 5 {G = r(t)^m F(t)} **********************************************/

    c0 = clock();
    {
        fmpz_t pN;
        fmpz_poly_t t;

        fmpz_init(pN);
        fmpz_poly_init(t);

        fmpz_pow_ui(pN, p, prec->N2 - vF);

        /* Compute r(t)^m mod p^{N2-vF} */
        if (prec->denR == NULL)
        {
            fmpz_mod_poly_t _t;

            fmpz_mod_poly_init(_t, pN);
            fmpz_mod_poly_set_fmpz_poly(_t, r);
            fmpz_mod_poly_pow(_t, _t, prec->m);
            fmpz_mod_poly_get_fmpz_poly(t, _t);
            fmpz_mod_poly_clear(_t);
        }
        else
        {
            /* TODO: We don't really need a copy */
            fmpz_poly_set(t, prec->denR);
        }

        fmpz_poly_mat_scalar_mul_fmpz_poly(F, F, t);
        fmpz_poly_mat_scalar_mod_fmpz(F, F, pN);

        /* TODO: This should not be necessary? */
        fmpz_poly_mat_truncate(F, prec->K);

        fmpz_clear(pN);
        fmpz_poly_clear(t);
    }
    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
    if (verbose)
    {
        printf("Analytic continuation:\n");
        printf("  Time = %f\n", c);
        printf("\n");
        fflush(stdout);
    }

    /* Steps 6 and 7 *********************************************************/

    if (a == 1)
    {
        /* Step 6 {F(1) = r(t_1)^{-m} G(t_1)} ********************************/

        c0 = clock();
        {
            const long N = prec->N2 - vF;

            fmpz_t f, g, t, pN;

            fmpz_init(f);
            fmpz_init(g);
            fmpz_init(t);
            fmpz_init(pN);

            fmpz_pow_ui(pN, p, N);

            /* f := \hat{t_1}, g := r(\hat{t_1})^{-m} */
            _padic_teichmuller(f, t1->coeffs + 0, p, N);
            if (prec->denR == NULL)
            {
                _fmpz_mod_poly_evaluate_fmpz(g, r->coeffs, r->length, f, pN);
                fmpz_powm_ui(t, g, prec->m, pN);
            }
            else
            {
                _fmpz_mod_poly_evaluate_fmpz(t, prec->denR->coeffs, prec->denR->length, f, pN);
            }
            _padic_inv(g, t, p, N);

            /* F1 := g G(\hat{t_1}) */
            for (i = 0; i < b; i++)
                for (j = 0; j < b; j++)
                {
                    const fmpz_poly_struct *poly = fmpz_poly_mat_entry(F, i, j);
                    const long len               = poly->length;

                    if (len == 0)
                    {
                        fmpz_poly_zero(fmpz_poly_mat_entry(F1, i, j));
                    }
                    else
                    {
                        fmpz_poly_fit_length(fmpz_poly_mat_entry(F1, i, j), 1);

                        _fmpz_mod_poly_evaluate_fmpz(t, poly->coeffs, len, f, pN);
                        fmpz_mul(fmpz_poly_mat_entry(F1, i, j)->coeffs + 0, g, t);
                        fmpz_mod(fmpz_poly_mat_entry(F1, i, j)->coeffs + 0,
                                 fmpz_poly_mat_entry(F1, i, j)->coeffs + 0, pN);

                        _fmpz_poly_set_length(fmpz_poly_mat_entry(F1, i, j), 1);
                        _fmpz_poly_normalise(fmpz_poly_mat_entry(F1, i, j));
                    }
                }

            vF1 = vF;
            fmpz_poly_mat_canonicalise(F1, &vF1, p);

            fmpz_clear(f);
            fmpz_clear(g);
            fmpz_clear(t);
            fmpz_clear(pN);
        }
        c1 = clock();
        c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
        if (verbose)
        {
            printf("Evaluation:\n");
            printf("  Time = %f\n", c);
            printf("\n");
            fflush(stdout);
        }
    }
    else
    {
        /* Step 6 {F(1) = r(t_1)^{-m} G(t_1)} ********************************/

        c0 = clock();
        {
            const long N = prec->N2 - vF;
            fmpz_t pN;
            fmpz *f, *g, *t;

            fmpz_init(pN);

            f = _fmpz_vec_init(a);
            g = _fmpz_vec_init(2 * a - 1);
            t = _fmpz_vec_init(2 * a - 1);

            fmpz_pow_ui(pN, p, N);

            /* f := \hat{t_1}, g := r(\hat{t_1})^{-m} */
            _qadic_teichmuller(f, t1->coeffs, t1->length, Qq->a, Qq->j, Qq->len, p, N);
            if (prec->denR == NULL)
            {
                fmpz_t e;
                fmpz_init_set_ui(e, prec->m);
                _fmpz_mod_poly_compose_smod(g, r->coeffs, r->length, f, a,
                                            Qq->a, Qq->j, Qq->len, pN);
                _qadic_pow(t, g, a, e, Qq->a, Qq->j, Qq->len, pN);
                fmpz_clear(e);
            }
            else
            {
                _fmpz_mod_poly_reduce(prec->denR->coeffs, prec->denR->length, Qq->a, Qq->j, Qq->len, pN);
                _fmpz_poly_normalise(prec->denR);

                _fmpz_mod_poly_compose_smod(t, prec->denR->coeffs, prec->denR->length, f, a,
                                            Qq->a, Qq->j, Qq->len, pN);
            }
            _qadic_inv(g, t, a, Qq->a, Qq->j, Qq->len, p, N);

            /* F1 := g G(\hat{t_1}) */
            for (i = 0; i < b; i++)
                for (j = 0; j < b; j++)
                {
                    const fmpz_poly_struct *poly = fmpz_poly_mat_entry(F, i, j);
                    const long len               = poly->length;

                    fmpz_poly_struct *poly2 = fmpz_poly_mat_entry(F1, i, j);

                    if (len == 0)
                    {
                        fmpz_poly_zero(poly2);
                    }
                    else
                    {
                        _fmpz_mod_poly_compose_smod(t, poly->coeffs, len, f, a,
                                                    Qq->a, Qq->j, Qq->len, pN);

                        fmpz_poly_fit_length(poly2, 2 * a - 1);
                        _fmpz_poly_mul(poly2->coeffs, g, a, t, a);
                        _fmpz_mod_poly_reduce(poly2->coeffs, 2 * a - 1, Qq->a, Qq->j, Qq->len, pN);
                        _fmpz_poly_set_length(poly2, a);
                        _fmpz_poly_normalise(poly2);
                    }
                }

            /* Now the matrix for p^{-1} F_p at t=t_1 is (F1, vF1). */
            vF1 = vF;
            fmpz_poly_mat_canonicalise(F1, &vF1, p);

            fmpz_clear(pN);
            _fmpz_vec_clear(f, a);
            _fmpz_vec_clear(g, 2 * a - 1);
            _fmpz_vec_clear(t, 2 * a - 1);
        }
        c1 = clock();
        c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
        if (verbose)
        {
            printf("Evaluation:\n");
            printf("  Time = %f\n", c);
            printf("\n");
            fflush(stdout);
        }

        /* Step 7 {Norm} *****************************************************/
        /*
            Computes the matrix for $q^{-1} F_q$ at $t = t_1$ as the
            product $F \sigma(F) \dotsm \sigma^{a-1}(F)$ up appropriate
            transpositions because our convention of columns vs rows is
            the opposite of that used by Gerkmann.

            Note that, in any case, transpositions do not affect
            the characteristic polynomial.
         */

        c0 = clock();
        {
            const long N = prec->N1 - a * vF1;

            fmpz_t pN;
            fmpz_poly_mat_t T;

            fmpz_init(pN);
            fmpz_poly_mat_init(T, b, b);

            fmpz_pow_ui(pN, p, N);

            fmpz_poly_mat_frobenius(T, F1, 1, p, N, Qq);
            _qadic_mat_mul(F1, F1, T, pN, Qq);

            for (i = 2; i < a; i++)
            {
                fmpz_poly_mat_frobenius(T, T, 1, p, N, Qq);
                _qadic_mat_mul(F1, F1, T, pN, Qq);
            }

            vF1 = a * vF1;
            fmpz_poly_mat_canonicalise(F1, &vF1, p);

            fmpz_clear(pN);
            fmpz_poly_mat_clear(T);
        }
        c1 = clock();
        c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
        if (verbose)
        {
            printf("Norm:\n");
            printf("  Time = %f\n", c);
            printf("\n");
            fflush(stdout);
        }
    }

    /* Step 8 {Reverse characteristic polynomial} ****************************/

    c0 = clock();

    deformation_revcharpoly(cp, F1, vF1, n, d, prec->N0, prec->r, prec->s, Qq);

    c1 = clock();
    c  = (double) (c1 - c0) / CLOCKS_PER_SEC;
    if (verbose)
    {
        printf("Reverse characteristic polynomial:\n");
        printf("  p(T) = "), fmpz_poly_print_pretty(cp, "T"), printf("\n");
        printf("  Time = %f\n", c);
        printf("\n");
        fflush(stdout);
    }

    /* Clean up **************************************************************/

    padic_mat_clear(F0);

    mat_clear(M, ctxFracQt);
    free(bR);
    free(bC);
    fmpz_poly_clear(r);

    fmpz_poly_mat_clear(C);
    fmpz_poly_mat_clear(Cinv);

    fmpz_poly_mat_clear(F);
    fmpz_poly_mat_clear(F1);
    fmpz_poly_clear(cp);
}