Calling function to evaluate another called function - delimeter error

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Michael Jacobson 2021-3-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/767006-calling-function-to-evaluate-another-called-function-delimeter-error

评论： Michael Jacobson 2021-3-9

采纳的回答： Walter Roberson

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I have two functions:

One for the Lee-Kesler state equation (name: lk)
One to find the root of an equation through the modified regular falsi method (name: wn). The inputs are (function to be evaluated, first root guess, second root guess, number of significant figures in final answer).

In a separate script, i am trying to call the mrf function to evaluate the lk equation as follows:

a=@wn(@lk,6,10,5)

However, when this is evaluated, I recieve the following error message:

Error: File: MainFunction.m Line: 51 Column: 18
Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for
mismatched delimiters.

I am not sure what is causing this, nor how to remedy it.

Thank you

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Answer 1

Walter Roberson 2021-3-9

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https://ww2.mathworks.cn/matlabcentral/answers/767006-calling-function-to-evaluate-another-called-function-delimeter-error#answer_642781

在 MATLAB Online 中打开

a = wn(@lk,6,10,5)

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Walter Roberson 2021-3-9

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Your function wn must currently start

function wn = wn(something)

where you have an output variable name the same as the function name. You should avoid doing that: you can get into complications with accidentally making the function recursive. Use a different output variable name than the function name. And make sure you assign to the output variable.

Another possibility that we cannot rule out at the moment is that you have

function wn = some_other_name(something)

but you stored the code in wn.m . The first function in the file is known according to its file name, so it is not an error to have the first function in the file have a different name than the file. It is, however, confusing.

A third possibility that we cannot rule out at the moment is that have

function wn = some_other_name(something)

and that you took at (non-confusing at the time)

some_function_handle = @some_other_name

but that you then later did

wn = some_function_handle

This is legal but confusing.

In all three cases, your code is not assigning to the (first) variable named on the left side of the "=" of the function file.

Walter Roberson 2021-3-9

在 MATLAB Online 中打开

function wn = wn(something)
end

That defines a function named wn but does not assign anything to the variable named wn

I suggest that you replace

function wn = wn(something)
end
%This is my function
function wn=mrf(f,a,b,n)

with

function Wn = wn(f,a,b,n)

Michael Jacobson 2021-3-9

@Walter RobersonAh that seems to have fixed the issue. Thank you very much for your help - I do appreciate it.

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