Usage: 3dLocalPV [options] inputdataset * You may want to use 3dDetrend before running this program,
or at least use the ‘-polort’ option.
This program is highly experimental. And slowish.
voxel. An inricate way of ‘smoothing’ 3D+time datasets, sort of.
allow anything but 1 and 2 dimensional projection. This is because 3dLocalPV uses a special method to compute JUST the first 1 or 2 principal vectors – faster than 3dLocalSVD, but less general.
Options:
-mask mset = restrict operations to this mask
-automask = create a mask from time series dataset
- -prefix ppp = save SVD vector result into this new dataset
- [default = ‘LocalPV’]
- -evprefix ppp = save singular value at each voxel into this dataset
- [default = don’t save]
-input inputdataset = input time series dataset
-nbhd nnn = e.g., ‘SPHERE(5)’ ‘TOHD(7)’ etc.
-despike = remove time series spikes from input dataset
-polort p = detrending
-vnorm = normalize data vectors [strongly recommended]
- -vproj [2] = project central data time series onto local SVD vector;
- if followed by ‘2’, then the central data time series will be projected on the the 2-dimensional subspace spanned by the first 2 principal SVD vectors. [default: just output principal singular vector] [for ‘smoothing’ purposes, ‘-vnorm -vproj’ is an idea]
Notes: * On my Mac Pro, about 30% faster than 3dLocalSVD computing the same thing. * If you’re curious, the ‘special method’ used for the eigensolution is
a variant of matrix power iteration, called ‘simultaneous iteration’.
automatic parallelizer software toolkit, which splits the work across multiple CPUs/cores on the same shared memory computer.
by a network (e.g., OpenMP doesn’t work with ‘cluster’ setups).
your system. You can control this value by setting environment variable OMP_NUM_THREADS to some smaller value (including 1).
using all CPUs available. ++ However, on some systems (such as the NIH Biowulf), it seems to be
necessary to set OMP_NUM_THREADS explicitly, or you only get one CPU.
count, since using more than (say) 16 threads is probably useless.
since OpenMP queries this variable BEFORE the program actually starts. ++ You can’t usefully set this variable in your ~/.afnirc file or on the
command line with the ‘-D’ option.
it was coded. You’ll have to experiment on your own systems!
The number of CPUs on this particular computer system is ...... 16.
The maximum number of CPUs that will be used is now set to .... 7.
++ Compile date = Dec 16 2015