【求助】Xwinnmr处理参数NC_proc的定义和计算

NC_proc - intensity scaling factor
• used in 1D, 2D and 3D datasets in the first dimension
• takes an integer value
• set by all processing commands
• only exists as processing status parameter
• Processing in XWIN-NMR performs calculations in double precision floating
point but stores the result in 32-bit integer values. During double to integer
conversion, the data are scaled up or down such that the highest intensity of
the spectrum lies between and . This means the 32 bit resolution is
not entirely used. This allows for the highest intensity to be increased, for
example during phase correction, without causing data overflow. NC_proc
shows the amount of scaling that was done, for example:
NC_proc = -3 : data were scaled up (multiplied by 2) three times
NC_proc = 4 : the data were scaled down (divided by 2) four times
228 229
P-36 XWIN-NMR parameters
DONE
INDEX
INDEX
• Although NC_proc is normally calculated by processing commands, 2D
processing also allows you to predefine the scaling factor with the argument
nc_proc, for example:
xfb nc_proc 2
scales down the data twice. However, you can only scale the data more down
(or less up) than the command would have done without the argument
nc_proc. The latter is shown by the processing status parameter NC_proc
(type dpp). Smaller (more negative) values of nc_proc are ignored to
avoid data overflow. The command:
xfb nc_proc last
takes the current value of the processing status parameter NC_proc (type
dpp) as input value.