what is the format of date variable imported from excel

Hi, I have imported two excels with first column as date and second column as numbers. Then I need to do some manipulation with the two set of data where I am using datenum. Anyway my code is as follows.

% nld=readtable('NLD.xls');

deu=readtable('deu.xls');
corresp = bsxfun( @eq, datenum( nld(:,1) ).',datenum( nld(:,1) )) ;
[r,c] = find( corresp ) ;

And I get the following warning and error message

    % Warning: Variable names were modified to make them valid MATLAB identifiers. 
> In makeValidName at 25
  In @table\private\setVarNames at 48
  In table.readXLSFile at 113
  In table.readFromFile at 35
  In readtable at 118
  In readdata at 2 
  Undefined function 'datetime' for input arguments of type 'cell'.
  Error in readdata (line 4)
  nld.Date = datetime(nld.Date,'InputFormat','MM/dd/yyyy')

Here is some sample of the imported variable nld

        Date        x10_Year
    ____________    ________

    '24/06/2015'    1.08    
    '23/06/2015'     1.1    
    '22/06/2015'    1.11    
    '19/06/2015'    1.01    
    '18/06/2015'    1.04    
    '17/06/2015'    1.08    
    '16/06/2015'    1.11    
    '15/06/2015'    1.09    
    '12/06/2015'    1.09    
    '11/06/2015'    1.09

Could you identify what is the problem here? Thanks for your help.

Cheers,

Xueqi

[Azzi Abdelmalek]

The data are correctly imported, now what is your problem? what do you want to achieve?

Answer 1

[Walter Roberson]

nlddate = datenum( nld{:,1} );
corresp = bsxfun( @eq, nlddate.', nlddate ) ;

[xueqi]

Thank you! It works! It seems that we need {} for tables!

[Peter Perkins]

xueqi, a couple things:

• You do not need {} for tables, you need {} for cell arrays of strings, which is what you have imported those datetimes in your file as. You will probably be happier specifying a %D format to readtable to read the strings in as datetimes, not as strings.
• The error you are getting

Undefined function 'datetime' for input arguments of type 'cell'.

indicates that there is something you have not told us.