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increasing precison of num2str for dlmcell function.

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function dlmcell(file,cell_array,varargin)
%%<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %%
% <><><><><> dlmcell - Write Cell Array to Text File <><><><><> %
% <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %
% Version: 01.06.2010 %
% (c) Roland Pfister %
% roland_pfister@t-online.de %
% ...with many thanks to George Papazafeiropoulos %
% for his corrections and improvements. %
% 1. Synopsis %
% %
% A single cell array is written to an output file. Cells may consist of %
% any combination of (a) numbers, (b) letters, or (c) words. The inputs %
% are as follows: %
% %
% - file The output filename (string). %
% - cell_array The cell array to be written. %
% - delimiter Delimiter symbol, e.g. ',' (optional; %
% default: tab ('\t'}). %
% - append '-a' for appending the content to the %
% output file (optional). %
% %
% 2. Example %
% %
% mycell = {'Numbers', 'Letters', 'Words','More Words'; ... %
% 1, 'A', 'Apple', {'Apricot'}; ... %
% 2, 'B', 'Banana', {'Blueberry'}; ... %
% 3, 'C', 'Cherry', {'Cranberry'}; }; %
% dlmcell('mytext.txt',mycell); %
% %
% <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %
%%Check input arguments
if nargin < 2
disp('Error - Give at least two input arguments!');
return;
elseif nargin > 4
disp('Error - Do not give more than 4 input arguments!');
return;
end
if ~ischar(file)
disp(['Error - File input has to be a string (e.g. ' ...
char(39) 'output.txt' char(39) '!']);
return;
end;
if ~iscell(cell_array)
disp('Error - Input cell_array not of the type "cell"!');
return;
end;
delimiter = '\t';
append = 'w';
if nargin > 2
for i = 1:size(varargin,2)
if strcmp('-a',varargin{1,i}) == 1
append = 'a';
else
delimiter = varargin{1,i};
end;
end;
end
%%Open output file and prepare output array.
output_file = fopen(file,append);
output = cell(size(cell_array,1),size(cell_array,2));
%%Evaluate and write input array.
for i = 1:size(cell_array,1)
for j = 1:size(cell_array,2)
if numel(cell_array{i,j}) == 0
output{i,j} = '';
% Check whether the content of cell i,j is
% numeric and convert numbers to strings.
elseif isnumeric(cell_array{i,j}) || islogical(cell_array{i,j})
output{i,j} = num2str(cell_array{i,j}(1,1));
% Check whether the content of cell i,j is another cell (e.g. a
% string of length > 1 that was stored as cell. If cell sizes
% equal [1,1], convert numbers and char-cells to strings.
%
% Note that any other cells-within-the-cell will produce errors
% or wrong results.
elseif iscell(cell_array{i,j})
if size(cell_array{i,j},1) == 1 && size(cell_array{i,j},1) == 1
if isnumeric(cell_array{i,j}{1,1})
output{i,j} = num2str(cell_array{i,j}{1,1}(1,1));
elseif ischar(cell_array{i,j}{1,1})
output{i,j} = cell_array{i,j}{1,1};
end;
end;
% If the cell already contains a string, nothing has to be done.
elseif ischar(cell_array{i,j})
output{i,j} = cell_array{i,j};
end;
% Cell i,j is written to the output file. A delimiter is appended for
% all but the last element of each row. At the end of a row, a newline
% is written to the output file.
if j < size(cell_array,2)
fprintf(output_file,['%s',delimiter],output{i,j});
else
fprintf(output_file,'%s\r\n',output{i,j});
end
end;
end;
%%Close output file.
fclose(output_file);
end
%when applying num2str function only 4 numbers after the point (floating point) extracting. Is there a way to increase the precision for doubles?

Accepted Answer

Robert Cumming
Robert Cumming on 30 Jun 2014
Edited: Robert Cumming on 30 Jun 2014
edit
So its not a display format issue, looking at the help for str2num you can see that it indicates that you can specify the precision, i.e.
change your line to:
num2str(cell_array{i,j}(1,1),10)
to make the number have extra decimal places in the string conversion
---------------------------------------------------------------------
Are you sure this isn't a display format issue:
str = '1.23456789'
>> str2num ( str )
ans =
1.2346
>> format long
>> str2num ( str )
ans =
1.234567890000000
  3 Comments
Robert Cumming
Robert Cumming on 30 Jun 2014
it works for me - on R2014a.
Another (better) solution is to write the number to file directly that way you don't need to do the conversion to a str, e.g:
fprintf ( output_file, '%8.6f%s', number, delimiter )

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