Nesting function trouble with undefined variable
显示 更早的评论
Trying to code a simple nesting function and I can't understand why I get an undefined function or variable warning for 'a'
function [Y] = nesty(d,e)
Y(d,e)=2*a;
nestmini
function [a] = nestmini(d,e)
a=d+e;
end
end
采纳的回答
Walter Roberson
2017-11-19
function [Y] = nesty(d,e)
a = nestmini;
Y(d,e)=2*a;
function [a] = nestmini(d,e)
a=d+e;
end
end
Remember, the variable named as output in a function is a dummy variable that is not assigned outside the function
5 个评论
@aldburg: KL gave you the correct solution already. The above answer is buggy, as it omits to call the nested function with the input arguments that you have defined it with:
function Y = nesty(d,e)
a = nestmini(d,e);
Y(d,e) = 2*a;
function a = nestmini(d,e)
a = d+e;
end
end
Although in that case there is absolutely no point in having written nestmini as a nested function, and nestmini could just be a local function. Perhaps you meant to pass d and e via the common workspace rather than as input arguments, which really makes use of nestmini being a nested function:
function Y = nesty(d,e)
a = nestmini();
Y(d,e) = 2*a;
function a = nestmini()
a = d+e;
end
end
Both of these work: I tested them.
aldburg
2017-11-19
@aldburg:
- Y=... defines a totally new variable with the name Y. It has the size of whatever the RHS has.
- Y(d,e)=... uses indexing to allocate values into the selected elements of Y. If Y does not exist before that indexing then MATLAB creates Y and fills the unindexed elements with zero.
The introductory tutorials teach these kind of basic MATLAB concepts, such as defining variables and using indexing, and are highly recommended for all beginners:
aldburg
2017-11-19
更多回答（1 个）
KL
2017-11-19
You're passing d,|e| to nesty function but you're using a on the right hand side of the equation. Do not expect matlab to call the nestmini function for you.
If you want to use the function return directly, try something like,
Y(d,e) = 2*nestmini(d,e);
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