How to properly use nargin

Question

Brendan Clark 2021-4-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/812940-how-to-properly-use-nargin

评论： Brendan Clark 2021-4-25

I'm trying to use nargin to set a default input for a function, should that default not be previously defined by the user. I'm setting up the nargin loop in the same format my teacher used, however, I'm getting an error saying N is undefined, which is technically the point. Irronically I ran my teachers function and it also had the same error... so I'm a little stuck at the moment.

This is my function at the moment.

function y = estimate_pi_Leibniz_Clark_Brendan(N)
if (nargin == 0)
    N = 10;
end 
p = 0 ; 
for k = 0:N
  p = p + 4*((-1)^(k)*(1/(2*k+1)));
end
y=p;

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Jonas 2021-4-25

looks good, how did you run your function?

Brendan Clark 2021-4-25

编辑：Brendan Clark 2021-4-25

I just attempted to run in by entering

y = estimate_pi_Leibniz_Clark_Brendan(N)

into the command window, when I preset N the function works exactly how its supposed to, it only kicks back an error when I attempt to run it without predetermining N.

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Answer 1

the cyclist 2021-4-25

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/812940-how-to-properly-use-nargin#answer_684410

编辑：the cyclist 2021-4-25

在 MATLAB Online 中打开

When you tried to call it like this:

y = estimate_pi_Leibniz_Clark_Brendan(N)

the problem is that in the calling workspace, the variable N does not exist, which is why you get that error. (The error is from the calling workspace, not from your function.)

Instead you could have called it as

y = estimate_pi_Leibniz_Clark_Brendan()

which would trigger your nargin statement.