Can I combine character data and numerical data in a fprintf statement

Hi I have found what I think is a bug. When I try writing to a text file, the %f format is not being correctly interpreted.

Date=str2mat('1889-01-01','1889-01-02','1889-01-03');
Data=[    2.4000    7.2511   25.5000   40.5000   24.0000    0.3254    1.7000;
  4.7000    7.4953   26.0000   41.0000   25.0000    0.3165    1.7000;
  0.3000    7.4547   25.0000   41.5000   25.0000    0.3184    1.7000];
fprintf(1,'%c%c%c%c%c%c%c%c%c%c,%5.2f,%5.2f,%5.2f,%5.2f,%5.2f,%5.2f,%5.2f\n',[Date,Data]');

Yields:

1889-01-01, 2.00, 7.00,25.00,40.00,24.00, 0.00, 1.00;
1889-01-02, 4.00, 7.00,26.00,41.00,25.00, 0.00, 1.00;
1889-01-03, 0.00, 7.00,25.00,41.00,25.00, 0.00, 1.00

Note the numerical data are not getting any precision after the decimal point.

Answer 1

[per isakson]

Yes, that is a bit strange. I made a little experiment:

    >> fprintf( 1, '%c,%7.3f\n', [ 122, pi, 122, pi ] )
    z,  3.142
    z,  3.142

and

    >> fprintf( 1, '%c,%7.3f\n', [ 'z', pi, 'z', pi ] )
    z,  3.000
    z,  3.000

.

concatenating < char> and < double> seems to be the problematic part.

    >> [ 'z', pi, 'z', pi ]
    ans =
    zz

    >> class( [ 'z', pi, 'z', pi ] )
    ans =
    char

.

Whether this is a bug or not depends on what the documentation says.

One more test:

    >> fprintf( 1, '%c,%7.3f\n', [ 'z', 20*pi, 'z', 20*pi ] )
    z, 62.000
    z, 62.000
    >> fprintf( 1, '%c,%7.3f\n', [ 'AZ'] )
    A, 90.000

and

    >> cast( cast( 20*pi, 'char' ), 'double' )
    ans =
        62

.

My guess is that this is documented behavior of concatenating < char> and < double>.

[Jan]

Another test:

class([3.14, 'a']);
class(['a', 3.14]);

Answer 2

[Thorsten]

The Matlab documentation says:

Combining character values with double values yields a character matrix. MATLAB converts the double elements in this example to their character equivalents

http://www.mathworks.de/de/help/matlab/matlab_prog/concatenation-examples.html

To get the desired output, you have to use something like this

for i = 1:size(Date, 1)
   fprintf('%s ', Date(i,:))
   fprintf('%5.2f ', Data(1,:))
   fprintf('\n')
end

or this

for i = 1:size(Date, 1), disp([Date(i,:) ' ' num2str(Data(1,:), '%5.2f ')]), end