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feat: added log-derivatives and symmetric effective mass

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This commit is contained in:
Simon Kuberski 2022-10-19 16:08:31 +02:00
parent 46c54a3f95
commit 9813f741f9
2 changed files with 65 additions and 2 deletions
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41
pyerrors/correlators.py
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@ -523,7 +523,7 @@ class Corr:
----------
variant : str
decides which definition of the finite differences derivative is used.
Available choice: symmetric, forward, backward, improved, default: symmetric
Available choice: symmetric, forward, backward, improved, log, default: symmetric
"""
if self.N != 1:
raise Exception("deriv only implemented for one-dimensional correlators.")
@ -567,6 +567,17 @@ class Corr:
if (all([x is None for x in newcontent])):
raise Exception('Derivative is undefined at all timeslices')
return Corr(newcontent, padding=[2, 2])
elif variant == 'log':
newcontent = []
for t in range(self.T):
if (self.content[t] is None) or (self.content[t] <= 0):
newcontent.append(None)
else:
newcontent.append(np.log(self.content[t]))
if (all([x is None for x in newcontent])):
raise Exception("Log is undefined at all timeslices")
logcorr = Corr(newcontent)
return self * logcorr.deriv('symmetric')
else:
raise Exception("Unknown variant.")
@ -577,7 +588,7 @@ class Corr:
----------
variant : str
decides which definition of the finite differences derivative is used.
Available choice: symmetric, improved, default: symmetric
Available choice: symmetric, improved, log, default: symmetric
"""
if self.N != 1:
raise Exception("second_deriv only implemented for one-dimensional correlators.")
@ -601,6 +612,17 @@ class Corr:
if (all([x is None for x in newcontent])):
raise Exception("Derivative is undefined at all timeslices")
return Corr(newcontent, padding=[2, 2])
elif variant == 'log':
newcontent = []
for t in range(self.T):
if (self.content[t] is None) or (self.content[t] <= 0):
newcontent.append(None)
else:
newcontent.append(np.log(self.content[t]))
if (all([x is None for x in newcontent])):
raise Exception("Log is undefined at all timeslices")
logcorr = Corr(newcontent)
return self * (logcorr.second_deriv('symmetric') + (logcorr.deriv('symmetric'))**2)
else:
raise Exception("Unknown variant.")
@ -615,6 +637,7 @@ class Corr:
sinh : Use anti-periodicitiy of the correlator by solving C(t) / C(t+1) = sinh(m * (t - T/2)) / sinh(m * (t + 1 - T/2)) for m.
See, e.g., arXiv:1205.5380
arccosh : Uses the explicit form of the symmetrized correlator (not recommended)
logsym: uses the symmetric effective mass log(C(t-1) / C(t+1))/2
guess : float
guess for the root finder, only relevant for the root variant
"""
@ -634,6 +657,20 @@ class Corr:
return np.log(Corr(newcontent, padding=[0, 1]))
elif variant == 'logsym':
newcontent = []
for t in range(1, self.T - 1):
if ((self.content[t - 1] is None) or (self.content[t + 1] is None)) or (self.content[t + 1][0].value == 0):
newcontent.append(None)
elif self.content[t - 1][0].value / self.content[t + 1][0].value < 0:
newcontent.append(None)
else:
newcontent.append(self.content[t - 1] / self.content[t + 1])
if (all([x is None for x in newcontent])):
raise Exception('m_eff is undefined at all timeslices')
return np.log(Corr(newcontent, padding=[1, 1])) / 2
elif variant in ['periodic', 'cosh', 'sinh']:
if variant in ['periodic', 'cosh']:
func = anp.cosh