MATLAB Programming

Saving and Loading MAT-Files
• Each variable to be saved must be either a two-dimensional double array
or a two-dimensional character array. Saving a complex double array
causestheimaginarypartofthedatatobelost,asMATLABcannotload
nonnumeric data ('i').
• ToreadthefilewiththeMATLABload function, make sure all the
variables have the same number of columns. If you are using a program
other than MATLAB to read the saved data, this restriction can be relaxed.
• Each MATLAB character in a character array is converted to a
floating-point number equal to its internal ASCII code and written out as a
floating-point number string. There is no information in the saved file that
indicates whether the value was originally a number or a character.
• The values of all variables saved merge into a single variable that takes
thenameoftheASCIIfile(minusanyextension). Therefore, it is advisable
to save only one variable at a time.
Saving in Version 4 Format. With the -v4 option, you can save only those
data constructs that are compatible with MATLAB Version 4. Therefore,
you cannot save structures, cell arrays, multidimensional arrays, or objects.
Variable names cannot exceed 19 characters in length. In addition, you must
use filenames that are supported by MATLAB Version 4.
Storage Requirements
The binary formats used by save depend on the size and type of each array.
Arrays with any noninteger entries and arrays with 10,000 or fewer elements
are saved in floating-point formats requiring 8 bytes per real element. Arrays
with all integer entries and more than 10,000 elements are saved in the
formats shown, requiring fewer bytes per element.
Element Range
0 to 255 1
0 to 65535 2
-32767 to 32767 2
-2 31 to 2 31 -1 4
Other 8
Bytes per Element
6-29