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How can I save MATLAB variables to a text file?

To save your matlab variables/arrays as ascii text, there are a number of things you can do. Here are some options in order of increasing difficultly:

  • For small matrices, you can use the "diary" command to create a diary file, and then list the variables on this file. You can then use your text editor to manipulate the diary file at a later time. The output of the diary includes the matlab commands used during the session. To turn the diary on, you simply enter a command of the form:
            diary filename

    To turn the diary off, just enter the command:

            diary off

    When using this method, you have some control the output format with the "format" command. See "help format" for more details.

  • You can save variables using the "save" command, with the /ascii option.
    For example:
            A = rand(4,3);
            save temp.dat A /ascii

    creates an ASCII file called temp.dat which contains something like:

            0.2113  0.8096  0.4832
            0.2115  0.7496  0.4483
            0.4813  0.5896  0.4383
            0.2373  0.5654  0.1934

    The format options are limited to either short or long floating point format with the "save" command.

  • Use the "fopen" and "fprintf" commands in Matlab to create your own custom format. These commands are similar to the ANSI C functions of the same name, with some extensions. Here is a simple example from "help fprintf". These statements
              >>  x = 0:.1:1; y = [x; exp(x)];
              >>  fid = fopen('exp.txt','w');
              >>  fprintf(fid,'%6.2f  %12.8f\n',y);

    create a text file containing a short table of the exponential function:

                0.00    1.00000000
                0.10    1.10517092
                1.00    2.71828183

IS&T Contributions

Documentation and information provided by IS&T staff members

Last Modified:

February 18, 2009

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