Intro information:  
### Gradient direction table for Human Connectome Project (HCP) dMRI (WU-Minn
### consortium). Each table acquired once with right-to-left and left-to-right
### phase encoding polarities, using the CMRR multiband diffusion sequence,
### with bmax = 3000 s/mm^2.  Shells at 1000, 2000, and 3000 s/mm^2 are
### obtained through appropriate weighting of the vector norm.
###
### The diffusion directions were obtained using a toolbox available from
### INRIA that returns uniformly distributed directions in multiple q-space
### shells.  The directions are optimized so that every subset of the first M
### directions is also isotropic. References and the INRIA toolbox can be
### found at:
### http://www-sop.inria.fr/members/Emmanuel.Caruyer/q-space-sampling.php
###
### NOTE: These gradient directions were tested for use on the HCP customized
### Skyra scanner with 100 mT/m gradients and may not be optimal for use with
### other scanner systems.
###
### Further questions can be directed to the HCP Data Users mailing list
### (hcp-user@humanconnectome.org) by signing up at
### http://www.humanconnectome.org/contact