md`# about the data
all data are saved in Matlab
* test.json is the first example in Matlab documentation.
> fid = fopen(filename,'w'); value = {'one'; 'two'; 'three'}; jsonencode(value); fclose(fid); (TO read into Matlab: text = fileread(filename); value = jsondecode(text);
* struct_vector.json is a struct.
> value.v1, value.v2, and value.v3 are vector coordinates.
* for mat_cell_vectors,
> value = {v1, v2, v3};
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