void
_elem_poly_sub(elem_ptr res, elem_srcptr poly1, long len1,
elem_srcptr poly2, long len2, const ring_t ring)
{
long i, min;
long size = ring->size;
if (ring->type == TYPE_FMPZ && 0)
{
_fmpz_poly_sub(res, poly1, len1, poly2, len2);
return;
}
min = FLINT_MIN(len1, len2);
for (i = 0; i < min; i++)
elem_sub(INDEX(res, i, size), SRC_INDEX(poly1, i, size), SRC_INDEX(poly2, i, size), ring);
if (poly1 != res)
for (i = min; i < len1; i++)
elem_set(INDEX(res, i, size), SRC_INDEX(poly1, i, size), ring);
for (i = min; i < len2; i++)
elem_neg(INDEX(res, i, size), SRC_INDEX(poly2, i, size), ring);
}
void _fmpz_mod_poly_sub(fmpz *res, const fmpz *poly1, long len1,
const fmpz *poly2, long len2, const fmpz_t p)
{
long i, len = FLINT_MAX(len1, len2);
_fmpz_poly_sub(res, poly1, len1, poly2, len2);
for (i = 0; i < len; i++)
{
if (fmpz_sgn(res + i) < 0)
fmpz_add(res + i, res + i, p);
}
}
void
fmpz_poly_sub(fmpz_poly_t res, const fmpz_poly_t poly1,
const fmpz_poly_t poly2)
{
slong max = FLINT_MAX(poly1->length, poly2->length);
fmpz_poly_fit_length(res, max);
_fmpz_poly_sub(res->coeffs, poly1->coeffs, poly1->length, poly2->coeffs,
poly2->length);
_fmpz_poly_set_length(res, max);
_fmpz_poly_normalise(res); /* there may have been cancellation */
}
void _padic_poly_sub(fmpz *rop, slong *val, slong N,
const fmpz *op1, slong val1, slong len1, slong N1,
const fmpz *op2, slong val2, slong len2, slong N2,
const padic_ctx_t ctx)
{
const slong len = FLINT_MAX(len1, len2);
*val = FLINT_MIN(val1, val2);
if (val1 == val2)
{
_fmpz_poly_sub(rop, op1, len1, op2, len2);
_padic_poly_canonicalise(rop, val, len, ctx->p);
}
else
{
fmpz_t x;
fmpz_init(x);
if (val1 < val2) /* F := p^g (G - p^{h-g} H) */
{
fmpz_pow_ui(x, ctx->p, val2 - val1);
if (rop == op1)
{
_fmpz_vec_zero(rop + len1, len2 - len1);
_fmpz_vec_scalar_submul_fmpz(rop, op2, len2, x);
}
else
{
_fmpz_vec_scalar_mul_fmpz(rop, op2, len2, x);
_fmpz_vec_neg(rop, rop, len2);
_fmpz_poly_add(rop, op1, len1, rop, len2);
}
}
else /* F := p^h (p^(g-h) G - H) */
{
fmpz_pow_ui(x, ctx->p, val1 - val2);
if (rop == op2)
{
_fmpz_vec_neg(rop, op2, len2);
_fmpz_vec_zero(rop + len2, len1 - len2);
_fmpz_vec_scalar_addmul_fmpz(rop, op1, len1, x);
}
else
{
_fmpz_vec_scalar_mul_fmpz(rop, op1, len1, x);
_fmpz_poly_sub(rop, rop, len1, op2, len2);
}
}
fmpz_clear(x);
}
/* Reduce */
if (N - *val > 0)
{
fmpz_t pow;
int alloc;
alloc = _padic_ctx_pow_ui(pow, N - *val, ctx);
if (N >= N1 && N >= N2)
{
slong i;
for (i = 0; i < len; i++)
if (fmpz_sgn(rop + i) < 0)
fmpz_add(rop + i, rop + i, pow);
}
else
{
_fmpz_vec_scalar_mod_fmpz(rop, rop, len, pow);
}
if (alloc)
fmpz_clear(pow);
}
else
{
_fmpz_vec_zero(rop, len);
*val = 0;
}
}
