Memory Requirements for Structure Array
Structure arrays do not require completely contiguous memory. However, each field requires
contiguous memory, as does the header that MATLAB creates to describe the array. For very large
arrays, incrementally increasing the number of fields or the number of elements in a field results in
Out of Memory errors.
Preallocate memory for the contents by assigning initial values with the struct function, such as
newStruct(1:25,1:50) = struct('a',ones(20),'b',zeros(30),'c',rand(40));
This code creates and populates a 25-by-50 structure array S with fields a, b, and c.
If you prefer not to assign initial values, you can initialize a structure array by assigning empty arrays
to each field of the last element in the structure array, such as
newStruct(25,50).a = [];
newStruct(25,50).b = [];
newStruct(25,50).c = [];
or, equivalently,
newStruct(25,50) = struct('a',[],'b',[],'c',[]);
However, in this case, MATLAB only allocates memory for the header, and not for the contents of the
array.
For more information, see:
• “Reshaping and Rearranging Arrays”
• “How MATLAB Allocates Memory” on page 31-12
11 Structures
11-18