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2970 bytes, as of the version from 2026-10-26 07:45. Recorded here, not run.
"""Jacobi theta₂ constants at singular nomes -- numberdb.org/T507.
Run with SageMath (install numberdb once with sage -pip install numberdb):
sage -python generate.py # verify every stored entry
sage -python generate.py --fill # write entries, not publication
sage -python checks.py # independent checks, no key needed
sage -python checks.py --stored # check stored draft, with API key
For authenticated operations set NUMBERDB_API_KEY, or pipe the key to stdin
with NUMBERDB_KEY_FROM_STDIN=1. No operation here publishes or offers a draft.
The parameter is a positive integer r, with tau=i*sqrt(r), q=exp(-pi*sqrt(r)).
The square root is positive, including when r has square factors. Store the
full theta-two constant, not a power or a period-normalized value. The initial
range 1..12 follows the common rectangular CM family.
Arb evaluates tau and the theta constant using ball arithmetic throughout.
The 96 guard bits give a 429-bit working precision for 100 significant digits.
The retained accuracy is measured by checks.py; each serialized decimal's
last-place interval must contain the entire computed ball.
"""
import os
import sys
import math
import numberdb.sage as numberdb
from sage.rings.complex_arb import ComplexBallField
WORKING_GUARD = 96
class ThetaTwoCM(numberdb.Generator):
table = 'T507'
parameters = ('r',)
type = 'R'
digits = 100
rigour = 'proven'
files = ('generate.py', 'checks.py', 'check.py', 'evidence.json')
def enumerate(self, limit=12):
for r in range(1, limit + 1):
yield {'r': r}
def value(self, params, digits):
r = int(params['r'])
if r < 1:
raise ValueError('r must be a positive integer')
C = ComplexBallField(numberdb.bits(digits, losing=WORKING_GUARD))
tau = C.gen(0) * C(r).sqrt()
z = C(0).jacobi_theta(tau)[1]
assert all(math.isfinite(float(t)) for part in (z.real(), z.imag())
for t in (part.mid(), part.rad()))
assert z.imag().contains_zero()
x = z.real()
assert x > 0 and x.accuracy() >= numberdb.bits(digits)
if r == 1:
return {'number': x,
'comment': r'The square lattice point $\tau_1=i$. Here $\theta_2(0,e^{-\pi})=\theta_4(0,e^{-\pi})$; its Gamma expression is CITE{formula-square}.',
'equals': 'HREF{Jacobi_theta₄_constants_at_singular_nomes#1}'}
return x
if __name__ == '__main__':
if os.environ.get('NUMBERDB_KEY_FROM_STDIN') == '1':
numberdb.configure(api_key=sys.stdin.read().strip())
generator = ThetaTwoCM()
if '--fill' in sys.argv or os.environ.get('NUMBERDB_PUBLISH') == '1':
print(generator.publish(message='Compute theta-two CM constants in ball arithmetic'))
else:
report = generator.verify(sample=None)
print(report)
sys.exit(0 if report.ok else 1)