MATLAB Programming

4 M-File Programming
Using nargin and nargout
When nargin or nargout appears in a nested function, it refers to the number
of inputs or outputs passed to that particular function, regardless of whether
ornotitisnested.
In the example shown above, nargin in function A is the number of inputs
passed to A, andnargin in function C is the number of inputs passed to C. Ifa
nested function needs the value of nargin or nargout from an outer function,
youcanpassthisvalueinasaseparateargument,asdoneinfunctionB.
Example of Passing Optional Arguments to Nested Functions
This example references the primary function’s varargin cell array from
each of two nested functions. (Because the workspace of an outer function is
shared with all functions nested within it, there is no need to pass varargin
to the nested functions.)
Both nested functions make use of the nargin value that applies to the
primary function. Calling nargin from the nested function would return the
number of inputs passed to that nested function, and not those that had been
passed to the primary. For this reason, the primary function must pass its
nargin value to the nested functions.
function meters = convert2meters(miles, varargin)
% Converts MILES (plus optional FEET and INCHES input)
% values to METERS.
if nargin < 1 || nargin > 3
error('1 to 3 input arguments are required');
end
function feet = convert2Feet(argsIn)
% Nested function that converts miles to feet and adds in
% optional FEET argument.
feet = miles .* 5280;
if argsIn >= 2
feet = feet + varargin{1};
end
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