sincsquared method, pure python, most general version

sincsquared_python_v1.py

def _zerosum_sincsquared(self,Delta=1):
    r"""
    ...
    """
    npi = self._pi
    twopi = 2*npi
    eg = self._euler_gamma

    t = Delta*twopi
    expt = exp(t)

    u = t*(-eg + log(RDF(self._N))/2 - log(twopi))
    w = RDF(npi**2/6-spence(1-RDF(1)/expt))

    y = RDF(0)
    n = int(0)
    while n < expt:
        n += 1
        cn  = self.cn(n)
        if cn!=0:
            logn = log(RDF(n))
            y += cn*(t-logn)

    return 2*(u+w+y)/(t**2)