UDXoutput2Ddata

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%   UDXoutput2Ddata(filename,p,t,u,attr_name,attr_rank,attr_shape,endfile)
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%   Outputs data in DX form.
%   Only one variable can be written to the file
%   variable must be a scalar, vector or tensor of doubles   
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%   x
%   attr_name  = name of the variable                   (type string)
%   attr_rank  = rank of variable data                  (0 for scalar, 1 for vector, etc.)
%   attr_shape = number of components of variable data  (assumed 1 for scalar)
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