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Help with Varargin

5 次查看（过去 30 天）
Joseph Hughes
Joseph Hughes 2011-3-23
I have a function called MySolve and i am looking to adapt it to use Varargin.
As far as i am aware Varargin allows defaults for parameters to be set. but can be over-ridden if an input is given. I am having trouble understanding the syntax for using Varargin, here is the function MySolve.m that i have written:
function [x,converged]=MySolve(f,x0,tol,maxit)
%Set Converged intial value to 0 (false)
%Set initial value of x as x0
converged=0;
x=x0;
%run a loop from 1 to maxit
for k=0:maxit
x1=x;
r=f(x);
J=MyJacobian(f,x,1e-6);
x=x-(J\r);
if(max(abs(x-x1)))<tol && max(abs(f(x)))<tol
converged=1;
end
end
I am looking to have defaults for tol and maxit as 1e-10 and 100 respectively.
any help is much appreciated.

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采纳的回答

Sarah Wait Zaranek
Sarah Wait Zaranek 2011-3-23
I would suggest the following. This way, the input values are reflected. Hardwire the inputs you definitely want, and use varargin to hold the optional inputs.
function [x,converged]=MySolve(f,x0,varargin)
optargin = size(varargin,2);
if optargin == 0
tol = 1e-10;
maxit = 100;
elseif optargin == 1
tol = varargin{1};
maxit = 100;
else
tol = varargin{1};
maxit = varargin{2};
end
  2 个评论
Joseph Hughes
Joseph Hughes 2011-3-23
works perfectly much appreciated :)
Sarah Wait Zaranek
Sarah Wait Zaranek 2011-3-23
No problem. Once you get the hang of it, varargin is sooo useful.

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更多回答（1 个）

Jarrod Rivituso
Jarrod Rivituso 2011-3-23
Actually you could use nargin to do this. Essentially, nargin tells you the number of the arguments, and you can use it add some code at the beginning of your function to compensate for missing inputs.
An example:
function twoInputs(x,y)
if nargin == 0
x = 1;
y = 2;
end
if nargin == 1
y = 2;
end
disp(x)
disp(y)

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