Why do I get Parse error ?

Question

Grégoire 2024-2-22

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编辑： Abhinay 2024-2-22

Hi,

I m trying to enter some new functions in my program and i keep getting "Parse error at x : usage might be invalid MATLABsyntax" when defining functions.

This one is an example i don t know what is wrong with it but it won't work

f = (@x) x+2

"invalid expression. Check for missing multipication operator..."

Can some of you help me please?

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Answer 1

Dyuman Joshi 2024-2-22

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在 MATLAB Online 中打开

The left parenthesis is supposed to be after the '@' symbol -

f = @(x) x +2
f = function_handle with value:
    @(x)x+2
f(3)
ans = 5

The general syntax is

name_of_function = @(independent_variables_separated_by_comma) relation_of_independent_variables
%e.g - function of 3 independent variables
g = @(x,y,z) x + y.*z
%same can be written as
G = @(X,Y,Z) X + Y.*Z

For more information, check out the following documentation pages - Function Handle

Anonymous Functions

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Dyuman Joshi 2024-2-22

You forgot to include the multiplication sign between 14 and x.

Note that MATLAB does not support implied multiplication, you have to specify the symbol.

Grégoire 2024-2-22

Okay noted,

thanks a lot for the help :)

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Answer 2

Abhinay 2024-2-22

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https://ww2.mathworks.cn/matlabcentral/answers/2085353-why-do-i-get-parse-error#answer_1414458

编辑：Abhinay 2024-2-22

在 MATLAB Online 中打开

I understand that you are getting an error "Parse error at x : usage might be invalid MATLABsyntax" when defining functions when you are trying to enter some new functions in your program.

The error you're seeing is because of a small mistake in the way you've written your function. To fix it, just remove the space between `@` and `(x)`. Here's how it should look:

f = @(x) x + 2;

Use this corrected line in your program, and it should work without the "Parse error".