Build an imat_ctrace from an ID and direction list.
tf=nd2ctrace(ids,dirs)
ND2CTRACE will construct an imat_ctrace from a vector of IDs (IDS) and directions (DIRS). It will create a coordinate for each combination of ID and direction.
ID must contain positive integers.
DIR can either be a list of integers, or a string or cell array of strings. If it contains integers, they must be in the range of -6 to 6, where 1 means X+, -3 means Z-, 0 means no direction, and so on.
>> t = nd2ctrace(1:10,1:3);
>> t = nd2ctrace(1:10,[-3 1 6]);
>> t = nd2ctrace(1:5,{'DIRA' 'DIRB'})
>>