Execute string containing MATLAB expression.

  EVAL(s), where s is a string, causes MATLAB to execute

  the string as an expression or statement.



  EVAL(s1,s2) provides the ability to catch errors.  It

  executes string s1 and returns if the operation was

  successful. If the operation generates an error,

  string s2 is evaluated before returning. Think of this

  as EVAL('try','catch')



  [X,Y,Z,...] = EVAL(s) returns output arguments from the

  expression in string s.



  The input strings to EVAL are often created by 

  concatenating substrings and variables inside square

  brackets. For example:



  Generate a sequence of matrices named M1 through M12:



      for n = 1:12

         eval(['M' num2str(n) ' = magic(n)'])




  Run a selected M-file script.  The strings making up 

  the rows of matrix D must all have the same length.



      D = ['odedemo '


           'fitdemo '];

      n = input('Select a demo number: ');




  Read and process files with names data1.dat, data2.dat, ...



      k = 0;

      while 1

         k = k+1;

         datak = ['data' int2str(k)];

         filename = [datak '.dat'];

         if ~exist(filename), break, end

         eval(['load ' filename]);

         X = eval(datak);

         % Process data in matrix X.