NMRPipe Processing Functions
REV: reverse spectrum.

Flag Argument Default Description
 -sw Adjust Sweep Width and ppm calibration.

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 FT -neg as shown below.


-sw 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 \

[ Home ] [ NIH ] [ NIDDK ] [ Disclaimer ] [ Copyright ]
last updated: Jul 24, 2011 / Webmaster