part
a vector of integers or a list of vectors of integers. If
it is a list, the vector part[[i]] specifies that the $i$-th dimension
of ja
should be partitioned into 1:(part[[i]][1]-1)
,
part[[i]][1]:(part[[i]][2]-1)
, and
part_hi
NULL or a vector of integers or a list of vector of integers
indicating the partioning at the higher end of each dimension. This means,
if it is a list, the values in the vector dim(ja)[i]-part_hi[[i]]
will be appended to the end of par