That is the correct fix for this problem. It has no side-effects. Some
scanners (eg: Siemens 7T) have coefficients of even higher orders, so you
can actually increase the siemens_cas to 100 or so to accommodate the full
range. That value just determines the preallocation, and the matrix is
trimmed down to the maximum appropriate size after reading the file.
I think this is going to be fixed in the next release of gradunwarp (though
when that will be...?)
On Sat, Oct 15, 2016 at 1:14 PM, Antonin Skoch <a...@ikem.cz> wrote:
> Dear experts,
> I have an issue with processing my data (acquired at Siemens Prisma 3T) by
> gradunwarp v1.0.2, downloaded from
> It crashed with my coef.grad file by producing "array index out of bounds"
> error in coef_file_parse routine.
> I managed to get it working by increasing siemens_cas=20 in core/globals.py
> The corrected images look reasonable, with deformation going to maximum
> approx 1-2 mm in off-isocenter regions.
> Since I am not familiar with internals of gradunwarp, I would like to
> assure myself the routine with my modification works OK and there is no
> other unwanted consequence by increasing siemens_cas. Could you please
> comment on?
> Antonin Skoch
> HCP-Users mailing list
> http://lists.humanconnectome.org/mailman/listinfo/hc p-users
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