You can also build nested cell arrays with direct assignments using the statements shown in step 3 above...

Indexing Nested Cell Arrays
To index nested cells, concatenate indexing expressions. The first set of
subscripts accesses the top layer of cells, and subsequent sets of parentheses
access successively deeper layers.
For example, array A has three levels of nesting:
cell 1,1
cell 1,2
17 24 1 8 15
5 2 8
23 5 7 14 16
7 3 0
'Test 1'
4 6 13 20 22
6 7 3
10 12 19 21 3
11 18 25 2 9
[2–4i 5+7i]
17
• To access the 5-by-5 array in cell (1,1), use A{1,1}.
• To access the 3-by-3 array in position (1,1) of cell (1,2), use A{1,2}{1,1}.
• To access the 2-by-2 cell array in cell (1,2), use A{1,2}.
• To access the empty cell in position (2,2) of cell (1,2), use
A{1,2}{2,2}{1,2}.
Converting Between Cell and Numeric Arrays
Use for loops to convert between cell and numeric formats. For example, create
a cell array F.
F{1,1} = [1 2; 3 4];
F{1,2} = [–1 0; 0 1];
20-30
Cell Arrays
F{2,1} = [7 8; 4 1];
F{2,2} = [4i 3+2i; 1–8i 5];
Now use three for loops to copy the contents of F into a numeric array NUM.
for k = 1:4
for m = 1:2
for n = 1:2
NUM(m,n,k) = F{k}(m,n);
end
end
end
Similarly, you must use for loops to assign each value of a numeric array to a
single cell of a cell array.
G = cell(1,16);
for m = 1:16
G{m} = NUM(m);
end
Cell Arrays of Structures
Use cell arrays to store groups of structures with different field architectures.
c_str = cell(1,2);
c_str{1}.label = '12/2/94 – 12/5/94';
c_str{1}.obs = [47 52 55 48; 17 22 35 11];
c_str{2}.xdata = [–0.03 0.41 1.98 2.12 17.11];
c_str{2}.ydata = [–3 5 18 0 9];
c_str{2}.zdata = [0.6 0.8 1 2.2 3.4];
cell 1
cell 2
c_str(1)
c_str(2)
.label
'12/2/94 – 12/5/94'
[–0.03 0.41 1.98 2.12 17.11]
.name
.test
47 52 55 48
.billing
[–3 5 18 0 9]
17 22 35 11
.test
[0.6 0.8 1 2.2 3.4]
Cell 1 of the c_str array contains a structure with two fields, one a string and
the other a vector. Cell 2 contains a structure with three vector fields.
20-31
20 Structures and Cell Arrays
When building cell arrays of structures, you must use content indexing.
Similarly, you must use content indexing to obtain the contents of structures
within cells. The syntax for content indexing is:
cell_array{index}.field
For example, to access the label field of the structure in cell 1, use
c_str{1}.label.
20-32
21
Function Handles
Benefits of Using Function Handles . . . . . . . . . 21-3
A Simple Function Handle . . . . . . . . . . . . . . . 21-5
Constructing a Function Handle . . . . . . . . . . . 21-7
Maximum Length of a Function Name . . . . . . . . . . 21-7
Evaluating a Function Through Its Handle . . . . . . 21-9
Function Evaluation and Overloading . . . . . . . . . . 21-9
Examples of Function Handle Evaluation . . . . . . . . 21-10
Displaying Function Handle Information . . . . . . 21-13
Fields Returned by the Functions Command . . . . . . 21-14
Types of Function Handles . . . . . . . . . . . . . . 21-17
Function Handle Operations . . . . . . . . . . . 21-21
Converting Function Handles to Function Names . . . . 21-21
Converting Function Names to Function Handles . . . . 21-22
Testing for Data Type . . . . . . . . . . . . . . . . 21-23
Testing for Equality . . . . . . . . . . . . . . . . 21-23
Saving and Loading Function Handles . . . . . . . 21-25
Handling Error Conditions . . . . . . . . . . . . 21-26
Handles to Nonexistent Functions . . . . . . . . . . . 21-26
Including Path In the Function Handle Constructor . . . 21-26
Evaluating a Nonscalar Function Handle . . . . . . . . 21-27
Historical Note - Evaluating Function Names . . . . 21-28

21 Function Handles
A function handle is a MATLAB data type that contains information used in
referencing a function. When you create a function handle, MATLAB stores in
the handle all the information about the function that it needs to execute, or
evaluate, it later on. Typically, a function handle is passed in an argument list
to other functions. It is then used in conjunction with feval to evaluate the
function to which the handle belongs.
A MATLAB function handle is more than just a reference to a function. It often
represents a collection of function methods, overloaded to handle different
argument types. When you create a handle to a function, MATLAB takes a
snapshot of all built-in and M-file methods of that name that are on the
MATLAB path and in scope at that time, and stores access information for all
of those methods in the handle.
When you evaluate a function handle, MATLAB considers only those functions
that were stored within the handle when it was created. Other functions that
might now be on the path or in scope are not considered. It is the combination
of which function methods are mapped to by the handle and what arguments
the handle is evaluated with that determines which is the actual function that
MATLAB dispatches to.
This chapter addresses the following topics:
• “Benefits of Using Function Handles”
• “Constructing a Function Handle”
• “Evaluating a Function Through Its Handle”
• “Displaying Function Handle Information”
• “Function Handle Operations”
• “Saving and Loading Function Handles”
• “Handling Error Conditions”
• “Historical Note - Evaluating Function Names”
21-2
Benefits of Using Function Handles
Benefits of Using Function Handles
Function handles enable you to do all of the following:
• Pass function access information to other functions
• Capture all methods of an overloaded function