NMRPipe Processing Functions
REV: reverse spectrum.
The REV function reverses the order of points
in each vector. Note that this is rarely the correct function
to apply to a "reversed" spectrum. This is because the zero-frequency
point of a spectrum is at point N/2 + 1 of 1 to N points.
This point should stay in the same position when the order of
frequencies is reversed. But, if the order of points is simply
reversed, the point that was previously at point N/2 + 1
will then be at point N/2. For this reason, a spectral dimension
which is reversed should instead be processed with
as shown below.
If this flag is used on frequency-domain data, the chemical
shift calibration information will be adjusted by the equivalent
of one point.
Negating imaginary data before Fourier transform is equivalent to applying the REV function followed by a one-point circular shift:
| nmrPipe -fn FT -neg \is equivalent to:
| nmrPipe -fn FT \ | nmrPipe -fn REV -sw \ | nmrPipe -fn CS -rs 1 -sw \