Optional input parameters in function definition causes problems when function is used during another function
2 次查看(过去 30 天)
显示 更早的评论
Dear all,
I have a function "density(d, r, k, dv, deltav)" where dv and deltav are optional inputs. To verify them i worked with:
if ~exist('dv','var')
do something
end
if exist('dv','var')
if ~exist('deltav','var')
do something else
end
end
in the definition of the function density. So I can call density(d,r,k) or density(d,r,k,dv) and it works. Now I have another function f2
function[a] = f2(other Inputs, d, r, dv, deltav)
...
for i = 1:n
k(i) = ...;
b = density(d, r, k(i), dv, deltav); %b is a Matrix %is in line 23 where the error occurs
a(i,:) = mean(b);
end
end
If I try now to call f2(other Inputs, d, r, dv) without deltav or even f2(other Inputs, d, r)
it gives me: Error using f2 (line 23) Not enough input arguments.
dv and deltav in f2 are only used in this specific line where density is called. So why do the "if exist" in density not work anymore? How can I solve this problem? Many thanks in advance
0 个评论
采纳的回答
Matt J
2015-1-2
编辑:Matt J
2015-1-2
So why do the "if exist" in density not work anymore?
They work just fine. It's f2() that is throwing the error message, not density().
The reason is that you didn't test for the existence of dv and deltav in f2's workspace as well. Since dv and deltav are referenced in line 23 of f2, f2 is trying to find them and cannot. The simplest solution is to use comma-separated-list expansion and varargin:
function [a] = f2(other Inputs, d, r, varargin)
...
for i = 1:n
k(i) = ...;
b = density(d, r, k(i), varargin{:}); %The {:} is important
a(i,:) = mean(b);
end
end
3 个评论
Matt J
2015-1-2
编辑:Matt J
2015-1-2
Not sure I follow the question. My use of varargin above avoids any testing of existence at all!
When you have to, the standard way to analyze the number of input arguments is with nargin, as Star Strider mentioned. I think exist(...,'var') is often a safer way, however, because if you later decide to change the number, order, or names of your inputs, exist(...,'var') commands will likely stay valid, whereas nargin processing will have to be reorganized.
更多回答(0 个)
另请参阅
产品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!