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spectrum.cc
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132 lines (118 loc) · 3.06 KB
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//
// Copyright 2018 The Simons Foundation, Inc. - All Rights Reserved.
//
// 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
//
// http://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.
//
#include <algorithm>
#include <utility>
#include "itensor/spectrum.h"
using std::move;
namespace itensor {
struct OrderSecond
{
template<typename PairType>
bool
operator()(PairType const& i, PairType const& j) const
{
return i.second > j.second;
}
};
Spectrum::
Spectrum(Args const& args)
: truncerr_(NAN)
{
computeTruncerr(args);
}
Spectrum::
Spectrum(Vector && eigs, Args const& args)
: eigs_(move(eigs))
{
computeTruncerr(args);
}
Spectrum::
Spectrum(Vector && eigs,
QNStorage && qns,
Args const& args)
: eigs_(move(eigs)),
qns_(move(qns))
{
computeTruncerr(args);
}
QN Spectrum::
qn(int n) const
{
if(qns_.empty()) return QN();
return qns_.at(n-1);
}
void Spectrum::
read(std::istream& s)
{
Error("Spectrum::read not currently implemented");
//s.read((char*)&truncerr_,sizeof(truncerr_));
//eigs_.read(s);
//size_t sz = 0;
//s.read((char*)&sz,sizeof(sz));
//qns_.resize(sz);
//for(size_t j = 0; j < sz; ++j)
// {
// s.read((char*)&qns_[j],sizeof(qns_[j]));
// }
}
void Spectrum::
write(std::ostream& s) const
{
Error("Spectrum::read not currently implemented");
//s.write((char*)&truncerr_,sizeof(truncerr_));
//eigs_.write(s);
//size_t sz = qns_.size();
//s.write((char*)&sz,sizeof(sz));
//for(size_t j = 0; j < sz; ++j)
// {
// s.write((char*)&qns_[j],sizeof(qns_[j]));
// }
}
void Spectrum::
computeTruncerr(Args const& args)
{
if(args.defined("Truncerr"))
{
truncerr_ = args.getReal("Truncerr");
return;
}
if(eigs_.size() > 0)
{
// Note: This only makes sense if the spectrum was normalized before truncation.
// Otherwise this will mostly return zero.
truncerr_ = 1.-sumels(eigs_);
if(truncerr_ < 0) truncerr_ = 0;
}
}
std::ostream&
operator<<(std::ostream & s, Spectrum const& spec)
{
auto& eigs = spec.eigsKept();
auto N = eigs.size();
if(N > 0)
{
decltype(N) max_show = 20;
auto stop = std::min(N,max_show);
s << " Eigs kept:";
for(auto j : range(stop))
{
s << format(eigs(j) > 1E-3 ? (" %.3f") : (" %.3E"), eigs(j));
}
s << format("\n Trunc. error = %.3E\n", spec.truncerr());
}
return s;
}
} //namespace itensor