pqc/external/flint-2.4.3/nmod_vec/doc/nmod_vec.txt

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/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2010 William Hart
******************************************************************************/
*******************************************************************************
Memory management
*******************************************************************************
mp_ptr _nmod_vec_init(slong len)
Returns a vector of the given length. The entries are not necessarily
zero.
void _nmod_vec_clear(mp_ptr vec)
Frees the memory used by the given vector.
*******************************************************************************
Modular reduction and arithmetic
*******************************************************************************
void nmod_init(nmod_t * mod, mp_limb_t n)
Initialises the given \code{nmod_t} structure for reduction modulo $n$
with a precomputed inverse.
NMOD_RED2(r, a_hi, a_lo, mod)
Macro to set $r$ to $a$ reduced modulo \code{mod.n}, where $a$
consists of two limbs \code{(a_hi, a_lo)}. The \code{mod} parameter
must be a valid \code{nmod_t} structure. It is assumed that \code{a_hi}
is already reduced modulo \code{mod.n}.
NMOD_RED(r, a, mod)
Macro to set $r$ to $a$ reduced modulo \code{mod.n}. The \code{mod}
parameter must be a valid \code{nmod_t} structure.
NMOD2_RED2(r, a_hi, a_lo, mod)
Macro to set $r$ to $a$ reduced modulo \code{mod.n}, where $a$
consists of two limbs \code{(a_hi, a_lo)}. The \code{mod} parameter
must be a valid \code{nmod_t} structure. No assumptions are made
about \code{a_hi}.
NMOD_RED3(r, a_hi, a_me, a_lo, mod)
Macro to set $r$ to $a$ reduced modulo \code{mod.n}, where $a$
consists of three limbs \code{(a_hi, a_me, a_lo)}. The \code{mod}
parameter must be a valid \code{nmod_t} structure. It is assumed
that \code{a_hi} is already reduced modulo \code{mod.n}.
NMOD_ADDMUL(r, a, b, mod)
Macro to set $r$ to $r + ab$ reduced modulo \code{mod.n}. The
\code{mod} parameter must be a valid \code{nmod_t} structure. It is
assumed that $r$, $a$, $b$ are already reduced modulo \code{mod.n}.
mp_limb_t _nmod_add(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $a + b$ modulo \code{mod.n}. It is assumed that \code{mod} is
no more than \code{FLINT_BITS - 1} bits. It is assumed that $a$ and $b$
are already reduced modulo \code{mod.n}.
mp_limb_t nmod_add(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $a + b$ modulo \code{mod.n}. No assumptions are made about
\code{mod.n}. It is assumed that $a$ and $b$ are already reduced
modulo \code{mod.n}.
mp_limb_t _nmod_sub(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $a - b$ modulo \code{mod.n}. It is assumed that \code{mod}
is no more than \code{FLINT_BITS - 1} bits. It is assumed that
$a$ and $b$ are already reduced modulo \code{mod.n}.
mp_limb_t nmod_sub(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $a - b$ modulo \code{mod.n}. No assumptions are made about
\code{mod.n}. It is assumed that $a$ and $b$ are already reduced
modulo \code{mod.n}.
mp_limb_t nmod_neg(mp_limb_t a, nmod_t mod)
Returns $-a$ modulo \code{mod.n}. It is assumed that $a$ is already
reduced modulo \code{mod.n}, but no assumptions are made about the
latter.
mp_limb_t nmod_mul(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $ab$ modulo \code{mod.n}. No assumptions are made about
\code{mod.n}. It is assumed that $a$ and $b$ are already reduced
modulo \code{mod.n}.
mp_limb_t nmod_inv(mp_limb_t a, nmod_t mod)
Returns $a^{-1}$ modulo \code{mod.n}. The inverse is assumed to exist.
mp_limb_t nmod_div(mp_limb_t a, mp_limb_t b, nmod_t mod)
Returns $a^{-1}$ modulo \code{mod.n}. The inverse of $b$ is assumed to
exist. It is assumed that $a$ is already reduced modulo \code{mod.n}.
mp_limb_t nmod_pow_ui(mp_limb_t a, ulong e, nmod_t mod)
Returns $a^e$ modulo \code{mod.n}. No assumptions are made about
\code{mod.n}. It is assumed that $a$ is already reduced
modulo \code{mod.n}.
*******************************************************************************
Random functions
*******************************************************************************
void _nmod_vec_randtest(mp_ptr vec, flint_rand_t state, slong len, nmod_t mod)
Sets \code{vec} to a random vector of the given length with entries
reduced modulo \code{mod.n}.
*******************************************************************************
Basic manipulation and comparison
*******************************************************************************
void _nmod_vec_set(mp_ptr res, mp_srcptr vec, slong len)
Copies \code{len} entries from the vector \code{vec} to \code{res}.
void _nmod_vec_zero(mp_ptr vec, slong len)
Zeros the given vector of the given length.
void _nmod_vec_swap(mp_ptr a, mp_ptr b, slong length)
Swaps the vectors \code{a} and \code{b} of length $n$ by actually
swapping the entries.
void _nmod_vec_reduce(mp_ptr res, mp_srcptr vec, slong len, nmod_t mod)
Reduces the entries of \code{(vec, len)} modulo \code{mod.n} and set
\code{res} to the result.
mp_bitcnt_t _nmod_vec_max_bits(mp_srcptr vec, slong len)
Returns the maximum number of bits of any entry in the vector.
int _nmod_vec_equal(mp_srcptr vec, mp_srcptr vec2, slong len)
Returns~$1$ if \code{(vec, len)} is equal to \code{(vec2, len)},
otherwise returns~$0$.
*******************************************************************************
Arithmetic operations
*******************************************************************************
void _nmod_vec_add(mp_ptr res, mp_srcptr vec1,
mp_srcptr vec2, slong len, nmod_t mod)
Sets \code{(res, len)} to the sum of \code{(vec1, len)}
and \code{(vec2, len)}.
void _nmod_vec_sub(mp_ptr res, mp_srcptr vec1,
mp_srcptr vec2, slong len, nmod_t mod)
Sets \code{(res, len)} to the difference of \code{(vec1, len)}
and \code{(vec2, len)}.
void _nmod_vec_neg(mp_ptr res, mp_srcptr vec, slong len, nmod_t mod)
Sets \code{(res, len)} to the negation of \code{(vec, len)}.
void _nmod_vec_scalar_mul_nmod(mp_ptr res, mp_srcptr vec,
slong len, mp_limb_t c, nmod_t mod)
Sets \code{(res, len)} to \code{(vec, len)} multiplied by $c$.
void _nmod_vec_scalar_addmul_nmod(mp_ptr res, mp_srcptr vec,
slong len, mp_limb_t c, nmod_t mod)
Adds \code{(vec, len)} times $c$ to the vector \code{(res, len)}.
*******************************************************************************
Dot products
*******************************************************************************
int _nmod_vec_dot_bound_limbs(slong len, nmod_t mod)
Returns the number of limbs (0, 1, 2 or 3) needed to represent the
unreduced dot product of two vectors of length \code{len} having entries
modulo \code{mod.n}, assuming that \code{len} is nonnegative and that
\code{mod.n} is nonzero. The computed bound is tight. In other words,
this function returns the precise limb size of \code{len} times
\code{(mod.n - 1) ^ 2}.
macro NMOD_VEC_DOT(res, i, len, expr1, expr2, mod, nlimbs)
Effectively performs the computation
\begin{verbatim}
res = 0;
for (i = 0; i < len; i++)
res += (expr1) * (expr2);
\end{verbatim}
but with the arithmetic performed modulo \code{mod}.
The \code{nlimbs} parameter should be 0, 1, 2 or 3, specifying the
number of limbs needed to represent the unreduced result.
mp_limb_t _nmod_vec_dot(mp_srcptr vec1, mp_srcptr vec2,
slong len, nmod_t mod, int nlimbs)
Returns the dot product of (\code{vec1}, \code{len}) and
(\code{vec2}, \code{len}). The \code{nlimbs} parameter should be
0, 1, 2 or 3, specifying the number of limbs needed to represent the
unreduced result.
mp_limb_t
_nmod_vec_dot_ptr(mp_srcptr vec1, const mp_ptr * vec2, slong offset, slong len,
nmod_t mod, int nlimbs)
Returns the dot product of (\code{vec1}, \code{len}) and the values at
\code{vec2[i][offset]}. The \code{nlimbs} parameter should be
0, 1, 2 or 3, specifying the number of limbs needed to represent the
unreduced result.