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NumbTh.h
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NumbTh.h
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/* Copyright (C) 2012-2020 IBM Corp.
* This program is Licensed under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
* https://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. See accompanying LICENSE file.
*/
#ifndef HELIB_NUMBTH_H
#define HELIB_NUMBTH_H
/**
* @file NumbTh.h
* @brief Miscellaneous utility functions.
**/
#include <algorithm>
#include <vector>
#include <set>
#include <cmath>
#include <complex>
#include <string>
#include <climits>
#include <cmath>
#include <iostream>
#include <fstream>
#include <sstream>
#include <ctime>
#include <memory>
#include <NTL/version.h>
#include <NTL/ZZ.h>
#include <NTL/ZZX.h>
#include <NTL/ZZ_p.h>
#include <NTL/ZZ_pX.h>
#include <NTL/xdouble.h>
#include <NTL/mat_GF2.h>
#include <NTL/mat_GF2E.h>
#include <NTL/GF2XFactoring.h>
#include <NTL/mat_lzz_p.h>
#include <NTL/mat_lzz_pE.h>
#include <NTL/lzz_pXFactoring.h>
#include <NTL/GF2EX.h>
#include <NTL/lzz_pEX.h>
#include <NTL/FFT.h>
// Test for the "right version" of NTL (currently 11.0.0)
#if (NTL_MAJOR_VERSION < 11)
#error "This version of HElib requires NTL version 11.0.0 or above"
#endif
#include <helib/assertions.h>
#include <helib/apiAttributes.h>
namespace helib {
extern const long double PI;
namespace FHEglobals {
//! @brief A dry-run flag
//! The dry-run option disables most operations, to save time. This lets
//! us quickly go over the evaluation of a circuit and estimate the
//! resulting noise magnitude, without having to actually compute anything.
extern bool dryRun;
//! @brief A list of required automorphisms
//! When non-nullptr, causes Ctxt::smartAutomorphism to just record the
//! requested automorphism rather than actually performing it. This can
//! be used to get a list of needed automorphisms for certain operations
//! and then generate all these key-switching matrices. Should only be
//! used in conjunction with dryRun=true
extern std::set<long>* automorphVals;
extern std::set<long>* automorphVals2;
} // namespace FHEglobals
inline bool setDryRun(bool toWhat = true)
{
return (FHEglobals::dryRun = toWhat);
}
inline bool isDryRun() { return FHEglobals::dryRun; }
inline void setAutomorphVals(std::set<long>* aVals)
{
FHEglobals::automorphVals = aVals;
}
inline bool isSetAutomorphVals()
{
return FHEglobals::automorphVals != nullptr;
}
inline void recordAutomorphVal(long k) { FHEglobals::automorphVals->insert(k); }
inline void setAutomorphVals2(std::set<long>* aVals)
{
FHEglobals::automorphVals2 = aVals;
}
inline bool isSetAutomorphVals2()
{
return FHEglobals::automorphVals2 != nullptr;
}
inline void recordAutomorphVal2(long k)
{
FHEglobals::automorphVals2->insert(k);
}
typedef long LONG; // using this to identify casts that we should
// really get rid of at some point in the future
/**
* @brief Considers `bits` as a vector of bits and returns the value it
* represents when interpreted as a n-bit 2's complement number, where n is
* given by `bitSize`.
* @param bits The value containing the bits to be reinterpreted.
* @param bitSize The number of bits to use, taken from the least significant
* end of `bits`.
* @return The value of the reinterpreted number as a long.
**/
long bitSetToLong(long bits, long bitSize);
//! @brief Routines for computing mathematically correct mod and div.
//!
//! mcDiv(a, b) = floor(a / b), mcMod(a, b) = a - b*mcDiv(a, b);
//! in particular, mcMod(a, b) is 0 or has the same sign as b
long mcMod(long a, long b);
long mcDiv(long a, long b);
//! Return balanced remainder. Assumes a in [0, q) and returns
//! balanced remainder in (-q/2, q/2]
inline long balRem(long a, long q)
{
if (a > q / 2)
return a - q;
else
return a;
}
//! Return the square of a number as a double
inline double fsquare(double x) { return x * x; }
//! Return multiplicative order of p modulo m, or 0 if GCD(p, m) != 1
long multOrd(long p, long m);
//! @brief Prime power solver.
//!
//! A is an n x n matrix, b is a length n (row) vector, this function finds a
//! solution for the matrix-vector equation x A = b. An error is raised if A
//! is not invertible mod p.
//!
//! NTL's current smallint modulus, zz_p::modulus(), is assumed to be p^r,
//! for p prime, r >= 1 integer.
void ppsolve(NTL::vec_zz_pE& x,
const NTL::mat_zz_pE& A,
const NTL::vec_zz_pE& b,
long p,
long r);
//! @brief A version for GF2: must have p == 2 and r == 1
void ppsolve(NTL::vec_GF2E& x,
const NTL::mat_GF2E& A,
const NTL::vec_GF2E& b,
long p,
long r);
//! @brief Compute the inverse mod p^r of an n x n matrix.
//!
//! NTL's current smallint modulus zz_p::modulus() is assumed to be p^r for
//! p prime, r >= 1 integer. For the zz_pE variant also zz_pE::modulus() must
//! be initialized. An error is raised if A is not invertible mod p.
void ppInvert(NTL::mat_zz_p& X, const NTL::mat_zz_p& A, long p, long r);
void ppInvert(NTL::mat_zz_pE& X, const NTL::mat_zz_pE& A, long p, long r);
// variants for GF2/GF2E to help with template code
inline void ppInvert(NTL::mat_GF2& X,
const NTL::mat_GF2& A,
UNUSED long p,
UNUSED long r)
{
NTL::inv(X, A);
}
inline void ppInvert(NTL::mat_GF2E& X,
const NTL::mat_GF2E& A,
UNUSED long p,
UNUSED long r)
{
NTL::inv(X, A);
}
void buildLinPolyMatrix(NTL::mat_zz_pE& M, long p);
void buildLinPolyMatrix(NTL::mat_GF2E& M, long p);
//! @brief Combination of buildLinPolyMatrix and ppsolve.
//!
//! Obtain the linearized polynomial coefficients from a vector L representing
//! the action of a linear map on the standard basis for zz_pE over zz_p.
//!
//! NTL's current smallint modulus, zz_p::modulus(), is assumed to be p^r,
//! for p prime, r >= 1 integer.
void buildLinPolyCoeffs(NTL::vec_zz_pE& C,
const NTL::vec_zz_pE& L,
long p,
long r);
//! @brief A version for GF2: must be called with p == 2 and r == 1
void buildLinPolyCoeffs(NTL::vec_GF2E& C,
const NTL::vec_GF2E& L,
long p,
long r);
//! @brief Apply a linearized polynomial with coefficient vector C.
//!
//! NTL's current smallint modulus, zz_p::modulus(), is assumed to be p^r,
//! for p prime, r >= 1 integer.
void applyLinPoly(NTL::zz_pE& beta,
const NTL::vec_zz_pE& C,
const NTL::zz_pE& alpha,
long p);
//! @brief A version for GF2: must be called with p == 2 and r == 1
void applyLinPoly(NTL::GF2E& beta,
const NTL::vec_GF2E& C,
const NTL::GF2E& alpha,
long p);
//! Base-2 logarithm
inline double log2(const NTL::xdouble& x) { return log(x) * 1.442695040889; }
//! @brief Factoring by trial division, only works for N<2^{60}, only the
//! primes are recorded, not their multiplicity.
void factorize(std::vector<long>& factors, long N);
void factorize(std::vector<NTL::ZZ>& factors, const NTL::ZZ& N);
//! @brief Factoring by trial division, only works for N<2^{60}
//! primes and multiplicities are recorded
void factorize(NTL::Vec<NTL::Pair<long, long>>& factors, long N);
//! @brief Prime-power factorization
void pp_factorize(std::vector<long>& factors, long N);
//! Compute Phi(N) and also factorize N.
void phiN(long& phiN, std::vector<long>& facts, long N);
void phiN(NTL::ZZ& phiN, std::vector<NTL::ZZ>& facts, const NTL::ZZ& N);
//! Compute Phi(N).
long phi_N(long N);
//! Returns in gens a generating set for Zm* /<p>, and in ords the
//! order of these generators. Return value is the order of p in Zm*.
long findGenerators(std::vector<long>& gens,
std::vector<long>& ords,
long m,
long p,
const std::vector<long>& candidates = std::vector<long>());
//! Find e-th root of unity modulo the current modulus.
void FindPrimitiveRoot(NTL::zz_p& r, unsigned long e);
void FindPrimitiveRoot(NTL::ZZ_p& r, unsigned long e);
//! Compute mobius function (naive method as n is small).
long mobius(long n);
//! Compute cyclotomic polynomial.
NTL::ZZX Cyclotomic(long N);
//! Return a degree-d irreducible polynomial mod p
NTL::ZZX makeIrredPoly(long p, long d);
//! Find a primitive root modulo N.
long primroot(long N, long phiN);
//! Compute the highest power of p that divides N.
long ord(long N, long p);
inline bool is2power(long m)
{
long k = NTL::NextPowerOfTwo(m);
return (((unsigned long)m) == (1UL << k));
}
//! returns a pseudo-random number in uniform in [0, 1)
double RandomReal();
//! returns a pseudo-random number comomlex number z with |z| < 1
std::complex<double> RandomComplex();
// Returns a random mod p polynomial of degree < n
NTL::ZZX RandPoly(long n, const NTL::ZZ& p);
///@{
/**
* @brief Reduce all the coefficients of a polynomial modulo q.
*
* When abs=false reduce to interval (-q/2,...,q/2), when abs=true reduce
* to [0,q). When abs=false and q=2, maintains the same sign as the input.
*/
void PolyRed(NTL::ZZX& out, const NTL::ZZX& in, long q, bool abs = false);
void PolyRed(NTL::ZZX& out,
const NTL::ZZX& in,
const NTL::ZZ& q,
bool abs = false);
inline void PolyRed(NTL::ZZX& F, long q, bool abs = false)
{
PolyRed(F, F, q, abs);
}
inline void PolyRed(NTL::ZZX& F, const NTL::ZZ& q, bool abs = false)
{
PolyRed(F, F, q, abs);
}
void vecRed(NTL::Vec<NTL::ZZ>& out,
const NTL::Vec<NTL::ZZ>& in,
long q,
bool abs);
void vecRed(NTL::Vec<NTL::ZZ>& out,
const NTL::Vec<NTL::ZZ>& in,
const NTL::ZZ& q,
bool abs);
///@}
// The interface has changed so that abs defaults to false,
// which is more consistent with the other interfaces.
// Calls without any explicit value for abs should generate a
// "deprecated" warning.
void MulMod(NTL::ZZX& out, const NTL::ZZX& f, long a, long q, bool abs);
[[deprecated("Please use MulMod with explicit abs argument.")]] inline void
MulMod(NTL::ZZX& out, const NTL::ZZX& f, long a, long q)
{
MulMod(out, f, a, q, false);
}
inline NTL::ZZX MulMod(const NTL::ZZX& f, long a, long q, bool abs)
{
NTL::ZZX res;
MulMod(res, f, a, q, abs);
return res;
}
[[deprecated("Please use MulMod with explicit abs argument.")]] inline NTL::ZZX
MulMod(const NTL::ZZX& f, long a, long q)
{
NTL::ZZX res;
MulMod(res, f, a, q, false);
return res;
}
//! Multiply the polynomial f by the integer a modulo q
//! output coefficients are balanced (appropriately randomized for even q)
void balanced_MulMod(NTL::ZZX& out, const NTL::ZZX& f, long a, long q);
///@{
//! @name Some enhanced conversion routines
inline void convert(long& x1, const NTL::GF2X& x2) { x1 = rep(ConstTerm(x2)); }
inline void convert(long& x1, const NTL::zz_pX& x2) { x1 = rep(ConstTerm(x2)); }
void convert(NTL::vec_zz_pE& X, const std::vector<NTL::ZZX>& A);
void convert(NTL::mat_zz_pE& X, const std::vector<std::vector<NTL::ZZX>>& A);
void convert(std::vector<NTL::ZZX>& X, const NTL::vec_zz_pE& A);
void convert(std::vector<std::vector<NTL::ZZX>>& X, const NTL::mat_zz_pE& A);
void convert(NTL::Vec<long>& out, const NTL::ZZX& in);
void convert(NTL::Vec<long>& out, const NTL::zz_pX& in, bool symmetric = false);
void convert(NTL::Vec<long>& out, const NTL::GF2X& in);
void convert(NTL::ZZX& out, const NTL::Vec<long>& in);
void convert(NTL::GF2X& out, const NTL::Vec<long>& in);
// right now, this is just a place-holder...it may or may not
// eventually be further fleshed out
///@}
//! A generic template that resolves to NTL's conv routine
template <typename T1, typename T2>
void convert(T1& x1, const T2& x2)
{
NTL::conv(x1, x2);
}
//! Additional helpful conversion base cases
inline void convert(long& x1, bool x2) { x1 = x2; }
inline void convert(double& x1, bool x2) { x1 = x2; }
inline void convert(std::complex<double>& x1, bool x2) { x1 = x2; }
inline void convert(std::complex<double>& x1, long x2) { x1 = x2; }
inline void convert(std::complex<double>& x1, double x2) { x1 = x2; }
inline void convert(NTL::ZZX& x1, NTL::GF2 x2) { x1 = rep(x2); }
inline void convert(NTL::ZZX& x1, NTL::zz_p x2) { x1 = rep(x2); }
//! generic vector conversion routines
template <typename T1, typename T2>
void convert(std::vector<T1>& v1, const std::vector<T2>& v2)
{
long n = v2.size();
v1.resize(n);
for (long i = 0; i < n; i++) {
// Applying static_cast<const T2&> to avoid issues when std::vector<T2>
// operator[] returns a non-T2 object (this happens for std::vector<bool>
// that returns a __bit_const_reference object).
convert(v1[i], static_cast<const T2&>(v2[i]));
}
}
template <typename T1, typename T2>
void convert(std::vector<T1>& v1, const NTL::Vec<T2>& v2)
{
long n = v2.length();
v1.resize(n);
for (long i = 0; i < n; i++)
convert(v1[i], v2[i]);
}
template <typename T1, typename T2>
void convert(NTL::Vec<T1>& v1, const std::vector<T2>& v2)
{
long n = v2.size();
v1.SetLength(n);
for (long i = 0; i < n; i++) {
// Applying static_cast<const T2&> to avoid issues when std::vector<T2>
// operator[] returns a non-T2 object (this happens for std::vector<bool>
// that returns a __bit_const_reference object).
convert(v1[i], static_cast<const T2&>(v2[i]));
}
}
//! Trivial type conversion, useful for generic code
template <typename T>
void convert(std::vector<T>& v1, const std::vector<T>& v2)
{
v1 = v2;
}
template <typename T1, typename T2>
T1 convert(const T2& v2)
{
T1 v1;
convert(v1, v2);
return v1;
}
template <typename T>
std::vector<T> vector_replicate(const T& a, long n)
{
std::vector<T> res;
res.resize(n);
for (long i = 0; i < n; i++)
res[i] = a;
return res;
}
template <typename T>
std::vector<T> Vec_replicate(const T& a, long n)
{
NTL::Vec<T> res;
res.SetLength(n);
for (long i = 0; i < n; i++)
res[i] = a;
return res;
}
// some unsafe conversions
inline void project(std::vector<double>& out,
const std::vector<std::complex<double>>& in)
{
long n = in.size();
out.resize(n);
for (long i = 0; i < n; i++)
out[i] = in[i].real();
}
inline void project_and_round(std::vector<long>& out,
const std::vector<std::complex<double>>& in)
{
long n = in.size();
out.resize(n);
for (long i = 0; i < n; i++)
out[i] = std::round(in[i].real());
}
//! returns \prod_d vec[d]
long computeProd(const NTL::Vec<long>& vec);
long computeProd(const std::vector<long>& vec);
// some useful operations
void mul(std::vector<NTL::ZZX>& x, const std::vector<NTL::ZZX>& a, long b);
void div(std::vector<NTL::ZZX>& x, const std::vector<NTL::ZZX>& a, long b);
void add(std::vector<NTL::ZZX>& x,
const std::vector<NTL::ZZX>& a,
const std::vector<NTL::ZZX>& b);
//! @brief Finds whether x is an element of the set X of size sz,
//! Returns -1 it not and the location if true
long is_in(long x, int* X, long sz);
//! @brief Returns a CRT coefficient: x = (0 mod p, 1 mod q).
//! If symmetric is set then x \in [-pq/2, pq/2), else x \in [0,pq)
inline long CRTcoeff(long p, long q, bool symmetric = false)
{
long pInv = NTL::InvMod(p, q); // p^-1 mod q \in [0,q)
if (symmetric && 2 * pInv >= q)
return p * (pInv - q);
else
return p * pInv;
}
/**
* @brief Incremental integer CRT for vectors.
*
* Expects co-primes p,q with q odd, and such that all the entries in v1 are
* in [-p/2,p/2). Returns in v1 the CRT of vp mod p and vq mod q, as integers
* in [-pq/2, pq/2). Uses the formula:
* \f[ CRT(vp,p,vq,q) = vp + [(vq-vp) * p^{-1}]_q * p, \f]
* where [...]_q means reduction to the interval [-q/2,q/2). Notice that if
* q is odd then this is the same as reducing to [-(q-1)/2,(q-1)/2], which
* means that [...]_q * p is in [-p(q-1)/2, p(q-1)/2], and since vp is in
* [-p/2,p/2) then the sum is indeed in [-pq/2,pq/2).
*
* Return true is both vectors are of the same length, false otherwise
*/
template <class zzvec> // zzvec can be vec_NTL::ZZ, vec_long, or Vec<zz_p>
bool intVecCRT(NTL::vec_ZZ& vp, const NTL::ZZ& p, const zzvec& vq, long q);
/**
* @brief Find the index of the (first) largest/smallest element.
*
* These procedures are roughly just simpler variants of std::max_element and
* std::min_element. argmin/argmax are implemented as a template, so the code
* must be placed in the header file for the compiler to find it. The class T
* must have an implementation of operator> and operator< for this template to
* work.
* @tparam maxFlag A boolean value: true - argmax, false - argmin
**/
template <typename T, bool maxFlag>
long argminmax(std::vector<T>& v)
{
if (v.size() < 1)
return -1; // error: this is an empty array
unsigned long idx = 0;
T target = v[0];
for (unsigned long i = 1; i < v.size(); i++)
if (maxFlag) {
if (v[i] > target) {
target = v[i];
idx = i;
}
} else {
if (v[i] < target) {
target = v[i];
idx = i;
}
}
return (long)idx;
}
template <typename T>
long argmax(std::vector<T>& v)
{
return argminmax<T, true>(v);
}
template <typename T>
long argmin(std::vector<T>& v)
{
return argminmax<T, false>(v);
}
//! @brief A variant with a specialized comparison function
//! (*moreThan)(a,b) returns the comparison a>b
inline long argmax(std::vector<long>& v, bool (*moreThan)(long, long))
{
if (v.size() < 1)
return -INT_MAX; // error: this is an empty array
unsigned long idx = 0;
long target = v[0];
for (unsigned long i = 1; i < v.size(); i++)
if ((*moreThan)(v[i], target)) {
target = v[i];
idx = i;
}
return (long)idx;
}
// Check that x is in 1 += epsilon
inline bool closeToOne(const NTL::xdouble& x, long p)
{
double pinv = 1.0 / p;
return (x < (1.0 + pinv) && x > (1 - pinv));
}
// Use continued fractions to approximate a float x as x ~ a/b
std::pair<long, long> rationalApprox(double x, long denomBound = 0);
std::pair<NTL::ZZ, NTL::ZZ> rationalApprox(
NTL::xdouble x,
NTL::xdouble denomBound = NTL::xdouble(0.0));
/**
* @brief Facility for "restoring" the NTL PRG state.
*
* NTL's random number generation facility is pretty limited, and does not
* provide a way to save/restore the state of a pseudo-random stream. This
* class gives us that ability: Constructing a RandomState object uses the PRG
* to generate 512 bits and stores them. Upon destruction (or an explicit call
* to restore()), these bits are used to re-set the seed of the PRG. A typical
* usage of the class is as follows:
* \code
* {
* RandomState r; // save the random state
*
* SetSeed(something); // set the PRG seed to something
* ... // more code that uses the new PRG seed
*
* } // The destructor is called implicitly, PRG state is restored
* \endcode
**/
class RandomState
{
private:
NTL::ZZ state;
bool restored;
public:
RandomState()
{
RandomBits(state, 512);
restored = false;
}
//! Restore the PRG state of NTL
void restore()
{
if (!restored) {
SetSeed(state);
restored = true;
}
}
~RandomState() { restore(); }
private:
RandomState(const RandomState&); // disable copy constructor
RandomState& operator=(const RandomState&); // disable assignment
};
//! @brief Advance the input stream beyond white spaces and a single instance of
//! the char cc
void seekPastChar(std::istream& str, int cc);
//! @brief Reverse a vector in place
template <typename T>
void reverse(NTL::Vec<T>& v, long lo, long hi)
{
long n = v.length();
assertInRange(lo, 0l, hi, "Invalid argument: Bad interval", true);
assertTrue(hi < n, "Invalid argument: Interval exceeds vector size");
if (lo >= hi)
return;
for (long i = lo, j = hi; i < j; i++, j--)
swap(v[i], v[j]);
}
//! @brief Rotate a vector in place using swaps
// Example: rotate by 1 means [0 1 2 3] -> [3 0 1 2]
// rotate by -1 means [0 1 2 3] -> [1 2 3 0]
template <typename T>
void rotate(NTL::Vec<T>& v, long k)
{
long n = v.length();
if (n <= 1)
return;
k %= n;
if (k < 0)
k += n;
if (k == 0)
return;
reverse(v, 0, n - 1);
reverse(v, 0, k - 1);
reverse(v, k, n - 1);
}
// An experimental facility as it is annoying that vector::size() is an
// unsigned quantity. This leads to all kinds of annoying warning messages.
//! @brief Size of STL vector as a long (rather than unsigned long)
template <typename T>
inline long lsize(const std::vector<T>& v)
{
return (long)v.size();
}
//! NTL/std compatibility
// Utility functions, release memory of std::vector and NTL::Vec
template <typename T>
void killVec(std::vector<T>& vec)
{
std::vector<T>().swap(vec);
}
template <typename T>
void killVec(NTL::Vec<T>& vec)
{
vec.kill();
}
// Set length to zero, but don't necessarily release memory
template <typename T>
void setLengthZero(std::vector<T>& vec)
{
if (vec.size() > 0)
vec.resize(0, vec[0]);
}
template <typename T>
void setLengthZero(NTL::Vec<T>& vec)
{
if (vec.length() > 0)
vec.SetLength(0, vec[0]);
}
template <typename T>
inline long lsize(const NTL::Vec<T>& v)
{
return v.length();
}
template <typename T>
void resize(NTL::Vec<T>& v, long sz, const T& val)
{
return v.SetLength(sz, val);
}
template <typename T>
void resize(std::vector<T>& v, long sz, const T& val)
{
return v.resize(sz, val);
}
template <typename T>
void resize(NTL::Vec<T>& v, long sz)
{
return v.SetLength(sz);
}
template <typename T>
void resize(std::vector<T>& v, long sz)
{
return v.resize(sz);
}
//! @brief Testing if two vectors point to the same object
// Believe it or not, this is really the way to do it...
template <typename T1, typename T2>
bool sameObject(const T1* p1, const T2* p2)
{
return dynamic_cast<const void*>(p1) == dynamic_cast<const void*>(p2);
}
//! @brief Modular composition of polynomials: res = g(h) mod f
void ModComp(NTL::ZZX& res,
const NTL::ZZX& g,
const NTL::ZZX& h,
const NTL::ZZX& f);
//! @brief Evaluates a modular integer polynomial, returns poly(x) mod p
long polyEvalMod(const NTL::ZZX& poly, long x, long p);
//! @brief Interpolate polynomial such that poly(x[i] mod p)=y[i] (mod p^e)
//! It is assumed that the points x[i] are all distinct modulo p
void interpolateMod(NTL::ZZX& poly,
const NTL::vec_long& x,
const NTL::vec_long& y,
long p,
long e = 1);
//! @brief returns ceiling(a/b); assumes a >=0, b>0, a+b <= MAX_LONG
inline long divc(long a, long b) { return (a + b - 1) / b; }
//! @class zz_pXModulus1
//! @brief Auxiliary classes to facilitate faster reduction mod Phi_m(X)
//! when the input has degree less than m
class zz_pXModulus1
{
public:
long m;
NTL::zz_pX f;
long n;
bool specialLogic;
long k, k1;
NTL::fftRep R0, R1;
NTL::zz_pXModulus fm; // just in case...
zz_pXModulus1(long _m, const NTL::zz_pX& _f);
const NTL::zz_pXModulus& upcast() const { return fm; }
};
void rem(NTL::zz_pX& r, const NTL::zz_pX& a, const zz_pXModulus1& ff);
//! placeholder for pXModulus ...no optimizations
class ZZ_pXModulus1 : public NTL::ZZ_pXModulus
{
public:
ZZ_pXModulus1(UNUSED long _m, const NTL::ZZ_pX& _f) : NTL::ZZ_pXModulus(_f) {}
const NTL::ZZ_pXModulus& upcast() const { return *this; }
};
template <typename T>
std::ostream& operator<<(std::ostream& s, std::vector<T> v)
{
if (v.size() == 0)
return (s << "[]");
s << '[';
for (long i = 0; i < (long)v.size() - 1; i++)
s << v[i] << ' ';
return (s << v[v.size() - 1] << ']');
}
template <typename T>
std::istream& operator>>(std::istream& s, std::vector<T>& v)
{
NTL::Vec<T> vv; // read into an NTL vector, then convert
s >> vv;
convert(v, vv);
return s;
}
template <typename T>
std::string vecToStr(const std::vector<T>& v)
{
std::stringstream ss;
ss << v;
return ss.str();
}
template <typename T>
NTL::Vec<T> atoVec(const char* a)
{
NTL::Vec<T> v;
std::string s(a);
std::stringstream ss(s);
ss >> v;
return v;
}
template <typename T>
std::vector<T> atovector(const char* a)
{
NTL::Vec<T> v1 = atoVec<T>(a);
std::vector<T> v2;
convert(v2, v1);
return v2;
}
#ifndef NTL_PROVIDES_TRUNC_FFT
// Define truncated FFT routines if not provided by NTL
inline void TofftRep_trunc(NTL::fftRep& y,
const NTL::zz_pX& x,
long k,
UNUSED long len,
long lo,
long hi)
{
TofftRep(y, x, k, lo, hi);
}
inline void TofftRep_trunc(NTL::fftRep& y,
const NTL::zz_pX& x,
long k,
long len)
{
TofftRep_trunc(y, x, k, len, 0, deg(x));
}
#endif
// Generic routines for computing absolute values and distances
// on real and complex numbers
template <typename T>
void AssertRealOrComplex()
{
static_assert(std::is_same<T, double>::value ||
std::is_same<T, std::complex<double>>::value,
"Error: type T is not double or std::complex<double>.");
}
template <typename T>
double Norm(const T& x)
{
AssertRealOrComplex<T>();
return std::abs(x);
}
template <typename T, typename U>
double Distance(const T& x, const U& y)
{
AssertRealOrComplex<T>();
AssertRealOrComplex<U>();
return std::abs(x - y);
}
// for vectors, we us the infty norm
template <typename T>
double Norm(const std::vector<T>& x)
{
long n = x.size();
double res = 0;
for (long i = 0; i < n; i++)
res = std::max(res, Norm(x[i]));
return res;
}
// we require same-length vectors
template <typename T, typename U>
double Distance(const std::vector<T>& x, const std::vector<U>& y)
{
assertTrue(x.size() == y.size(), "Distance: mismatched vector sizes");
long n = x.size();
double res = 0;
for (long i = 0; i < n; i++)
res = std::max(res, Distance(x[i], y[i]));
return res;
}
// General mechanisms for comparing approximate numbers
// returns true iff |x-y| <= tolerance*max(|y|,floor)
// the template mechanism will allow comparisons
// between scalars of real/complex types, or between vectors
// of real/complex types.
// For vectors, sizes must be equal and the infty norm is used
template <typename T, typename U>
inline bool approx_equal(const T& x, const U& y, double tolerance, double floor)
{
return Distance(x, y) <= tolerance * std::max(Norm(y), floor);
}
template <class T>
struct ApproxClass
{
const T& val;
double tolerance;
double floor;
ApproxClass(const T& val_, double tolerance_, double floor_) :
val(val_), tolerance(tolerance_), floor(floor_)
{}
};
template <class T>
ApproxClass<T> Approx(const T& val, double tolerance = 0.01, double floor = 1.0)
{
return ApproxClass<T>(val, tolerance, floor);
}
template <class T, class U>
bool operator==(const T& x, const ApproxClass<U>& y)
{
return approx_equal(x, y.val, y.tolerance, y.floor);
}
template <class T, class U>
bool operator!=(const T& x, const ApproxClass<U>& y)
{
return !approx_equal(x, y.val, y.tolerance, y.floor);
}
//! @brief Compute next power of two in floating point
//! NextPow2(x) returns 1 if x < 1, and otherwise returns
//! 2^(ceil(log2(x)))
double NextPow2(double x);
//! @brief Represents the set of long int's plus a distinguished value
//! that can be used to denote "undefined".
//! Similary in spirit to C++17's optional<long> type.
class OptLong
{
long data;
bool defined;