def contract_cpeps(cpeps,auxbond):
cmps0 = get_boundaryMPS(cpeps,'d')
for i in range(1,cpeps.shape[0]-1):
cmpo = get_rowMPO(cpeps,i)
cmps0 = mpo.mapply(cmpo,cmps0)
if auxbond is not None: # compress
cmps0 = mps.compress(cmps0,auxbond)
cmps1 = get_boundaryMPS(cpeps,'u')
return mps.dot(cmps0,cmps1)
def contract(mpo,mpsb,side,thresh,ncanonical=1):
"""
mapply->canonicalise->compress
"""
ret=mapply(mpo,mpsb)
# roundoff can cause problems,
# so do multiple canonicalisations
for i in xrange(ncanonical):
ret=mps.canonicalise(ret,side)
ret=mps.compress(ret,side,thresh)
return ret
def contract_cpeps(cpeps, auxbond):
cmps0 = [None] * cpeps.shape[1]
for i in range(cpeps.shape[1]):
l, u, d, r = cpeps[0, i].shape
cmps0[i] = np.reshape(cpeps[0, i], (l, u * d, r))
for i in range(1, cpeps.shape[0]):
cmpo = [None] * cpeps.shape[1]
for j in range(cpeps.shape[1]):
l, u, d, r = cpeps[i, j].shape
cmpo[j] = cpeps[i, j]
cmps0 = mpo.mapply(cmpo, cmps0)
if auxbond is not None: # compress
#print "compressing"
cmps0 = mps.compress(cmps0, "l", auxbond)
return mps.ceval(cmps0, [0] * cpeps.shape[1])
def contract(mpo,
mpsb,
side,
thresh,
mpsa=None,
ncanonical=1,
compress_method="svd"):
assert compress_method in ["svd", "variational"]
if compress_method == "svd":
"""
mapply->canonicalise->compress
"""
ret = mapply(mpo, mpsb)
# roundoff can cause problems,
# so do multiple canonicalisations
for i in xrange(ncanonical):
ret = mps.canonicalise(ret, side)
ret = mps.compress(ret, side, thresh)
elif compress_method == "variational":
if mpsa == None:
#mpsa = mps.add(mpsb,None)
mpox = mps.canonicalise(mpo, side)
mpsa = mapply(mpox, mpsb)
nloops = 1
ret = mps.variational_compress(mpsb,
mpsa,
mpo,
side,
nloops,
trunc=thresh,
method="1site")
return ret
def genBPEPO(pepo, Lphys, nf, auxbond=20):
auxbond_hor = auxbond
print '\n[genPEPOsmall.genBPEPO] auxbond=', auxbond, ' auxbond_hor=', auxbond_hor
ntot = pepo.shape[0]
Ltot = Lphys + nf * (Lphys - 1)
dist = nf + 1
nl = (ntot - Ltot) / 2
nr = ntot - nl - Ltot # >= nl
print ' ntot=', pepo.shape[0], '(Lphys,nf)=', (Lphys, nf)
print ' Ltot=', Ltot, ' dist=', dist, ' nl=', nl, ' nr=', nr, ' ratio=', float(
ntot) / Ltot
# Bottom MPS
bmps = [None] * ntot
for j in range(ntot):
l, u, d, r = pepo[0, j][0, 0].shape
assert d == 1
bmps[j] = pepo[0, j][0, 0].reshape(l, u * d, r)
# Compression
for i in range(1, nl):
cmpo = [None] * ntot
for j in range(ntot):
cmpo[j] = pepo[i, j][0, 0].copy()
bmps = contraction2d.mpo_mapply(cmpo, bmps)
if auxbond is not None: # compress
bmps = mps.compress(bmps, auxbond)
# Upper MPS -> Note that the MPO is not upper-lower symmetric !
umps = [None] * ntot
for j in range(ntot):
l, u, d, r = pepo[ntot - 1, j][0, 0].shape
assert u == 1
umps[j] = pepo[ntot - 1, j][0, 0].reshape(l, u * d, r)
# Compression
for i in range(ntot - 2, ntot - nr - 1, -1):
cmpo = [None] * ntot
for j in range(ntot):
cmpo[j] = pepo[i, j][0, 0].transpose(0, 2, 1,
3).copy() # ludr->ldur
umps = contraction2d.mpo_mapply(cmpo, umps)
if auxbond is not None: # compress
umps = mps.compress(umps, auxbond)
#
# TPEPO
#
tpepo = numpy.empty((Ltot + 2, ntot), dtype=numpy.object)
for j in range(ntot):
l, u, r = bmps[j].shape
tpepo[0, j] = bmps[j].reshape((1, 1, l, u, 1, r)) # Add physical index
for j in range(ntot):
l, d, r = umps[j].shape
tpepo[Ltot + 1, j] = umps[j].reshape(
(1, 1, l, 1, d, r)) # Add physical index
for i in range(Ltot):
for j in range(ntot):
tpepo[i + 1, j] = pepo[i + nl, j].copy()
# Left MPS
lmps = [None] * (Ltot + 2)
for i in range(Ltot + 2):
l, u, d, r = tpepo[i, 0][0, 0].shape
assert l == 1
lmps[i] = numpy.reshape(tpepo[i, 0][0, 0],
(u, d, r)).transpose(1, 2, 0) # udr->dru
for j in range(1, nl):
cmpo = [None] * (Ltot + 2)
for i in range(Ltot + 2):
cmpo[i] = tpepo[i, j][0, 0].transpose(2, 3, 0, 1) # ludr->drlu
lmps = contraction2d.mpo_mapply(cmpo, lmps)
if auxbond is not None: # compress
lmps = mps.compress(lmps, auxbond_hor)
# Right MPS
rmps = [None] * (Ltot + 2)
for i in range(Ltot + 2):
l, u, d, r = tpepo[i, ntot - 1][0, 0].shape
assert r == 1
rmps[i] = numpy.reshape(tpepo[i, ntot - 1][0, 0],
(l, u, d)).transpose(2, 0, 1) # lud->dlu
for i in range(1, nr):
cmpo = [None] * (Ltot + 2)
for j in range(Ltot + 2):
cmpo[j] = tpepo[j, ntot - i - 1][0, 0].transpose(2, 0, 3,
1) # ludr->dlru
rmps = contraction2d.mpo_mapply(cmpo, rmps)
if auxbond is not None: # compress
rmps = mps.compress(rmps, auxbond_hor)
#
# Assemble SPEPO
#
spepo = numpy.empty((Ltot + 2, Ltot + 2), dtype=numpy.object)
# Middle
for i in range(Ltot):
for j in range(Ltot):
spepo[i + 1, j + 1] = tpepo[i + 1, j + nl].copy()
# Left
for i in range(Ltot + 2):
d, r, u = lmps[i].shape
l = 1
tmp = numpy.reshape(lmps[i], (l, d, r, u)).transpose(0, 3, 1,
2) # ldru->ludr
spepo[i, 0] = tmp.reshape((1, 1, l, u, d, r))
# Right
for i in range(Ltot + 2):
d, l, u = rmps[i].shape
r = 1
tmp = numpy.reshape(rmps[i], (d, l, u, r)).transpose(1, 2, 0,
3) # dlur->ludr
spepo[i, Ltot + 1] = tmp.reshape((1, 1, l, u, d, r))
# Bottom
for j in range(Ltot):
spepo[0, j + 1] = tpepo[0, j + nl].copy()
# Up
for j in range(Ltot):
spepo[Ltot + 1, j + 1] = tpepo[Ltot + 1, j + nl].copy()
return spepo