how to delete this error?

Question

zero 2018-2-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/382639-how-to-delete-this-error

回答： Image Analyst 2018-2-15

function y = dd(x)
% x is a vector
% We create an output vector of only 0 (our default value)
y = zeros(1, length(x));
% We find indexes of input values equal to 0,
% and make them 1
y(find(x==0)) = 1;
 function y = dd(x)
 ↑
Error: Function definitions are not permitted in this context.

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Answer 1

Jos (10584) 2018-2-14

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or even shorter

y = ~x

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Jan 2018-2-14

+1, shortest.

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Answer 2

Jan 2018-2-14

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https://ww2.mathworks.cn/matlabcentral/answers/382639-how-to-delete-this-error#answer_305156

编辑：Jan 2018-2-14

在 MATLAB Online 中打开

Error: Function definitions are not permitted in this context.

This means, that you either try to create this function in the command window, or inside a script while using Matlab < R2016b.

Function can be defined in the editor inside an "M-function-file" (an M-file which starts with the keyword "function"), or with using a modern Matlab version in a "M-script-file" (an M-file not starting with "function").

By the way: As Birdman has mentioned already, the find() can be omitted:

y = zeros(1, length(x));
y(x==0) = 1;

Or even shorter:

y = (x == 0);

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Answer 3

Image Analyst 2018-2-15

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You are defining a function dd(x), but then at line 9 of that function you try to define a nested function with the very same name, dd(), nested inside the dd() function. That is, if you're ending your functions with the "end" keyword.

function y = dd(x)
% x is a vector
% We create an output vector of only 0 (our default value)
y = zeros(1, length(x));
% We find indexes of input values equal to 0,
% and make them 1
 y(find(x==0)) = 1;
 function y = dd(x)
 ↑
Error: Function definitions are not permitted in this context.

Why??? You can't do that. You already have a dd function, why would you want another one of the same name to be defined inside of it???

Or, if you're defining functions without the "end" keyword, then you're not nesting but you're defining two functions with the same name in the same m-file. Again, Why???? You can't do that.