https://github.com/ITensor/ITensor
Tip revision: dea79340a5f450ff6fc270c5fe37dc4c725fcb97 authored by Miles Stoudenmire on 13 November 2018, 10:57:27 UTC
Removed empty file svdalgs.h
Removed empty file svdalgs.h
Tip revision: dea7934
qn.cc
#include "itensor/qn.h"
#include "itensor/util/readwrite.h"
namespace itensor {
QN::
QN(qn_t q0)
{
qn_[0] = QNVal(q0);
}
QN::
QN(qn_t q0,
qn_t q1)
{
qn_[0] = QNVal(q0);
qn_[1] = QNVal(q1);
}
QN::
QN(qn_t q0,
qn_t q1,
qn_t q2)
{
qn_[0] = QNVal(q0);
qn_[1] = QNVal(q1);
qn_[2] = QNVal(q2);
}
QN::
QN(qn_t q0,
qn_t q1,
qn_t q2,
qn_t q3)
{
qn_[0] = QNVal(q0);
qn_[1] = QNVal(q1);
qn_[2] = QNVal(q2);
qn_[3] = QNVal(q3);
}
QN::
QN(Args const& args)
{
auto hasSz = args.defined("Sz");
auto start = hasSz ? 1 : 0;
if(hasSz) qn_[0] = QNVal(args.getInt("Sz"));
if(args.defined("Nb"))
{
qn_[start] = QNVal(args.getInt("Nb"),+1);
}
else if(args.defined("Nf"))
{
qn_[start] = QNVal(args.getInt("Nf"),-1);
}
else if(args.defined("Pf"))
{
qn_[start] = QNVal(args.getInt("Pf"),-2);
}
}
void QN::
modAssign(QN const& qo)
{
for(size_t n = 0; n < QNSize(); ++n)
{
qn_[n] = QNVal(qn_[n].val(),qo.qn_[n].mod());
}
}
void QNVal::
set(qn_t v)
{
auto m = std::abs(mod_);
if(m > 1)
{
// Here v is the value we want to compute mod m.
// If v >= 0 then it's enough to compute v%m.
// If v < 0 we don't want -(|v|%m) which is what
// C++'s v%m operation gives. Instead we want
// to map, say, -1 to m-1 and -m-1 to m-1 etc.
// Observe that m*|v| > v (since m > 1).
// So m*|v|+v for negative v will always be > 0
// and mod'ing this will give the desired behavior.
val_ = (m*std::abs(v)+v)%m;
}
else
{
val_ = v;
}
}
void
operator+=(QNVal& qva, QNVal const& qvb)
{
#ifdef DEBUG
if(qva.mod() != qvb.mod())
{
printfln("qva.mod()=%d, qvb.mod()=%d",qva.mod(),qvb.mod());
Error("Mismatched mod factors");
}
#endif
qva.set(qva.val()+qvb.val());
}
void
operator-=(QNVal& qva, QNVal const& qvb)
{
assert(qva.mod() == qvb.mod());
qva.set(qva.val()-qvb.val());
}
void
operator*=(QNVal& qva, Arrow dir)
{
qva.set(qva.val() * static_cast<int>(dir));
}
bool
operator==(QNVal const& qva, QNVal const& qvb)
{
assert(qva.mod() == qvb.mod());
return qva.val() == qvb.val();
}
bool
operator!=(QNVal const& qva, QNVal const& qvb)
{
assert(qva.mod() == qvb.mod());
return qva.val() != qvb.val();
}
void
read(std::istream & s, QNVal & q)
{
QNVal::qn_t v = 0,
m = 0;
itensor::read(s,v);
itensor::read(s,m);
q = QNVal(v,m);
}
void
write(std::ostream & s, QNVal const& q)
{
itensor::write(s,q.val());
itensor::write(s,q.mod());
}
void
printFull(QN const& q)
{
print("QN(");
for(auto n : range1(QNSize()))
{
if(!isActive(q,n)) break;
if(n > 1) print(",");
print("{",q(n),",",q.mod(n),"}");
}
println(")");
}
bool
operator==(QN const& qa, QN const& qb)
{
for(size_t n = 0; n < QNSize(); ++n)
{
if(qa.val0(n).val() != qb.val0(n).val()) return false;
}
return true;
}
bool
operator<(QN const& qa, QN const& qb)
{
for(size_t n = 0; n < QNSize(); ++n)
{
if(qa.val0(n).val() == qb.val0(n).val()) continue;
return qa.val0(n).val() < qb.val0(n).val();
}
return false;
}
QN
operator-(QN q)
{
for(size_t n = 0; n < QNSize(); ++n)
{
q.val0(n) = -q.val0(n);
}
return q;
}
void
operator+=(QN & qa, QN const& qb)
{
if(!qa) qa.modAssign(qb);
if(!qb) return;
for(size_t n = 0; n < QNSize() && isActive(qa.val0(n)); ++n)
{
qa.val0(n) += qb.val0(n);
}
}
void
operator-=(QN & qa, QN const& qb)
{
if(!qa) qa.modAssign(qb);
if(!qb) return;
for(size_t n = 0; n < QNSize() && isActive(qa.val0(n)); ++n)
{
qa.val0(n) -= qb.val0(n);
}
}
void
operator*=(QN & qa, Arrow dir)
{
for(size_t n = 0; n < QNSize() && isActive(qa.val0(n)); ++n)
{
qa.val0(n) *= dir;
}
}
std::ostream&
operator<<(std::ostream & s, QN const& q)
{
if(q.mod(1) == 1 && !isActive(q,2))
{
//spin or spinless boson
s << "QN(" << q(1) << ")";
}
else
if(q.mod(1) == -1 && !isActive(q,2))
{
//spinless fermion
s << "(Nf=" << q(1) << ")";
}
else
if(q.mod(1) == -2 && !isActive(q,2))
{
//parity-only spinless fermion
s << "(Pf=" << q(1) << ")";
}
else
if(q.mod(1) == 1 && q.mod(2) == -1 && !isActive(q,3))
{
//electron
s << "(Sz=" << q(1) << ",Nf=" << q(2) << ")";
}
else
if(q.mod(1) == 1 && q.mod(2) == -2 && !isActive(q,3))
{
//"superconducting" electron (parity conservation only)
s << "(Sz=" << q(1) << ",Pf=" << q(2) << ")";
}
else
{
//catch-all behavior
s << "QN(";
for(auto n : range1(QNSize()))
{
if(!isActive(q,n)) break;
if(n > 1) s << ",";
if(q.mod(n) != 1)
{
s << "{" << q(n) << "," << q.mod(n) << "}";
}
else
{
s << q(n);
}
}
s << ")";
}
return s;
}
int
paritySign(QN const& q)
{
int p = 1;
for(size_t n = 0; n < QNSize() && isActive(q.val0(n)); ++n)
{
if(isFermionic(q.val0(n)) && std::abs(q[n])%2==1)
{
p *= -1;
}
}
return p;
}
bool
isFermionic(QN const& q)
{
for(size_t n = 0; n < QNSize() && isActive(q.val0(n)); ++n)
{
if(isFermionic(q.val0(n))) return true;
}
return false;
}
void
read(std::istream & s, QN & q)
{
for(auto& el : q.store())
itensor::read(s,el);
}
void
write(std::ostream & s, QN const& q)
{
for(auto& el : q.store())
itensor::write(s,el);
}
} //namespace itensor