#!/usr/bin/python -Wall

# ----------------------------------------------------------------
# John Kerl
# kerl.john.r@gmail.com
# 2005-01-11
# (Ported to Python 2006-03-06)
#
# This is a radix-2 fast Fourier transform.  Example:
#
# bash$ cat a.txt
#      1 0.02
#      2 0.04
#      3 0.06
#      4 0.08
#      5 0.10
#      6 0.12
#      7 0.14
#      8 0.16
# bash$ pyfft a.txt
#     12.72792206136      0.25455844123
#     -1.48249783362      3.38592929113
#     -1.44249783362      1.38592929113
#     -1.42592929113      0.55750216638
#     -1.41421356237     -0.02828427125
#     -1.40249783362     -0.61407070887
#     -1.38592929113     -1.44249783362
#     -1.34592929113     -3.44249783362
# bash$ pyfft a.txt | pyfft -rev
#      1.00000000000      0.02000000001
#      2.00000000000      0.04000000000
#      3.00000000000      0.06000000000
#      4.00000000000      0.08000000000
#      5.00000000000      0.10000000000
#      6.00000000000      0.12000000000
#      7.00000000001      0.13999999999
#      8.00000000000      0.16000000000
#
# This file contains the I/O wrapper.  The library routine is in pyfft_m.py.
# ----------------------------------------------------------------
# This software is released under the terms of the GNU GPL.
# Please see LICENSE.txt in the same directory as this file.
# ================================================================

from __future__ import division # 1/2 = 0.5, not 0.
import sys
import pyfft_m
import pyrcio_m

# ----------------------------------------------------------------
def usage():
	print >> sys.stderr, "Usage:", sys.argv[0], "[options] [file name]"
	print >> sys.stderr, "If the file name is omitted, input is taken from standard input."
	print >> sys.stderr, "Format is in whitespace-delimited decimal rectangular, e.g."
	print >> sys.stderr, "  1.0 0.0"
	print >> sys.stderr, "  2.0 0.0"
	print >> sys.stderr, "  3.0 0.0"
	print >> sys.stderr, "  4.0 0.0"
	print >> sys.stderr, "Options:"
	print >> sys.stderr, "  -fi:  input folding"
	print >> sys.stderr, "  -nfi: no input folding"
	print >> sys.stderr, "  -fo:  output folding"
	print >> sys.stderr, "  -nfo: no output folding"
	print >> sys.stderr, "  -fwd: forward FFT (exp(-i 2 pi k/N) kernel)"
	print >> sys.stderr, "  -rev: reverse FFT (exp( i 2 pi k/N) kernel)"
	print >> sys.stderr, "  -s:   scaling"
	print >> sys.stderr, "  -ns:  no scaling"
	print >> sys.stderr, "  -dft: Use DFT.  Allows N not to be a power of 2."
	sys.exit(1)

# ================================================================
# Start of program
fold_in   = 0
fold_out  = 0
forward   = 1
scale     = 1
use_dft   = 0
file_name = "-"

argc = len(sys.argv)
argi = 1
while (argi < argc):
	arg = sys.argv[argi]
	if (arg[0] != '-'):
		break
	if   (arg == "-fi"):
		fold_in  = 1
	elif (arg == "-nfi"):
		fold_in  = 0
	elif (arg == "-fo"):
		fold_out = 1
	elif (arg == "-nfo"):
		fold_out = 0
	elif (arg == "-fwd"):
		forward  = 1
	elif (arg == "-rev"):
		forward  = 0
	elif (arg == "-s"):
		scale    = 1
	elif (arg == "-ns"):
		scale    = 0
	elif (arg == "-dft"):
		use_dft  = 1
	elif (arg == "-ndft"):
		use_dft  = 0
	else:
		usage()
	argi += 1

if ((argc - argi) == 1):
	file_name = sys.argv[argi]
elif ((argc - argi) == 0):
	file_name = "-"
else:
	usage()

u = pyrcio_m.read_complex_column_vector(file_name)
if (use_dft):
	v = pyfft_m.dft(u, fold_in, fold_out, forward, scale)
else:
	v = pyfft_m.fft(u, fold_in, fold_out, forward, scale)
pyrcio_m.print_complex_column_vector(v)