def xafsft(k, chi, group=None, kmin=0, kmax=20, kweight=0, dk=1, dk2=None,
window='kaiser', rmax_out=10, nfft=2048, kstep=0.05, _larch=None, **kws):
"""
calculate forward XAFS Fourier transform
"""
if _larch is None:
raise Warning("cannot do xafsft -- larch broken?")
# allow kweight keyword == kw
if 'kw' in kws:
kweight = kws['kw']
cchi, win = xafsft_prep(k, chi, kmin=kmin, kmax=kmax, kweight=kweight,
dk=dk, dk2=dk2, nfft=nfft, kstep=kstep,
window=window, _larch=_larch)
out = xafsft_fast(cchi*win, kstep=kstep, nfft=nfft)
rstep = pi/(kstep*nfft)
irmax = min(nfft/2, int(1.01 + rmax_out/rstep))
if _larch.symtable.isgroup(group):
r = rstep * arange(irmax)
mag = sqrt(out.real**2 + out.imag**2)
group.kwin = win[:len(chi)]
group.r = r[:irmax]
group.chir = out[:irmax]
group.chir_mag = mag[:irmax]
group.chir_pha = complex_phase(out[:irmax])
group.chir_re = out.real[:irmax]
group.chir_im = out.imag[:irmax]
else:
return out[:irmax]
def xafsift(r, chir, group=None, rmin=0, rmax=20,
dr=1, dr2=None, rw=0, window='kaiser', qmax_out=None,
nfft=2048, kstep=0.05, _larch=None, **kws):
"""
calculate reverse XAFS Fourier transform
This assumes that chir_re and (optional chir_im are
on a uniform r-grid given by r.
"""
if _larch is None:
raise Warning("cannot do xafsft -- larch broken?")
if 'rweight' in kws:
rw = kws['rweight']
rstep = r[1] - r[0]
kstep = pi/(rstep*nfft)
scale = 1.0
cchir = zeros(nfft, dtype='complex128')
r_ = rstep * arange(nfft, dtype='float64')
cchir[0:len(chir)] = chir
if chir.dtype == np.dtype('complex128'):
scale = 0.5
win = ftwindow(r_, xmin=rmin, xmax=rmax, dx=dr, dx2=dr2, window=window)
out = scale * xafsift_fast( cchir*win * r_**rw, kstep=kstep, nfft=nfft)
if qmax_out is None: qmax_out = 30.0
q = linspace(0, qmax_out, int(1.05 + qmax_out/kstep))
nkpts = len(q)
if _larch.symtable.isgroup(group):
group.q = q
mag = sqrt(out.real**2 + out.imag**2)
group.rwin = win[:len(chir)]
group.chiq_mag = mag[:nkpts]
group.chiq_pha = complex_phase(out[:nkpts])
group.chiq_re = out.real[:nkpts]
group.chiq_im = out.imag[:nkpts]
else:
return out[:nkpts]
def _xafsft(self, chi, group=None, rmax_out=10, **kws):
"returns "
for key, val in kws:
if key == 'kw':
key = 'kweight'
setattr(self, key, val)
self.make_karrays()
out = self.fftf(chi)
irmax = min(self.nfft/2, int(1.01 + rmax_out/self.rstep))
if self._larch.symtable.isgroup(group):
r = self.rstep * arange(irmax)
mag = sqrt(out.real**2 + out.imag**2)
group.kwin = self.kwin[:len(chi)]
group.r = r[:irmax]
group.chir = out[:irmax]
group.chir_mag = mag[:irmax]
group.chir_pha = complex_phase(out[:irmax])
group.chir_re = out.real[:irmax]
group.chir_im = out.imag[:irmax]
else:
return out[:irmax]
