>> files(k) = importfile('files.dat', 4, 128);
has the issue. In your code after executing the following line :
>> files = dir('*.dat');
variable files contains the names of all the files as a struct array. Its documentation is here. Each individual struct can be accessed by providing an index into the array, for example, files(2) gives access to the second struct in files. Since importfile() requires filename as the first argument, you will need to retrieve the name of the given file from the struct, for example, files(2).name. In the given loop, variable k is already counting the index, which you can use .
A possible replacement is :
temp_value = importfile(files(k).name, 4, 128);
However, you may want to implement the changes differently.
