Usage: 3dEmpty [options]
Makes an 'empty' dataset .HEAD file.

 -prefix p   = Prefix name for output file (default = 'Empty')

 -nxyz x y z = Set number of voxels to be 'x', 'y', and 'z'
                 along the 3 axes [defaults=64]

 -geometry m = Set the 3D geometry of the grid using a
               string 'm' of the form
               which defines the number of grid points, as well as
               relationship between grid indexes (voxel centers)
               and the 3D xyz coordinates.
             * Sample 'MATRIX()' entries can be found by using
               program 3dinfo on an existing datasets.
             * Each .niml file used by 3dGroupInCorr has a
               'geometry="MATRIX(...)" entry.

 -nt         = Number of time points [default=1]

* Other dataset parameters can be changed with 3drefit.
* The purpose of this program (combined with 3drefit) is to
  allow you to make up an AFNI header for an existing data file.
* This program does NOT create data to fill up the dataset.
* If you want to create a dataset of a given size with random
  values attached, a command like
    3dcalc -a jRandomDataset:32,32,16,10 -expr a -prefix Something
  would work. In this example, nx=ny=32 nz=16 nt=10.
  (Changing '-expr a' to '-expr 0' would fill the dataset with zeros.)

++ Compile date = Nov 12 2020 {AFNI_20.3.02:linux_ubuntu_16_64}