Add a option to function qtt_fft1() so that it is possible to turn off the bit reversion at the end of the procedure. This is for the preparation to be used in the multi-dimensional qtt-fft method in which the bit reversion is only done globally but not for every sub-train of the QTT.
This "turning off" of the bit reversion is based on the "Algorithm 3" in the paper:
S. Dolgov, B. Khoromskij, D. Savostyanov, Superfast Fourier transform using QTT approximation,
J. Fourier Anal. Appl., 18(5), 2012.
Add a option to function qtt_fft1() so that it is possible to turn off the bit reversion at the end of the procedure. This is for the preparation to be used in the multi-dimensional qtt-fft method in which the bit reversion is only done globally but not for every sub-train of the QTT.
This "turning off" of the bit reversion is based on the "Algorithm 3" in the paper: S. Dolgov, B. Khoromskij, D. Savostyanov, Superfast Fourier transform using QTT approximation, J. Fourier Anal. Appl., 18(5), 2012.