Problem with custom function

Question

Pietro Fiondella 2022-7-4

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1752990-problem-with-custom-function

编辑： Siraj 2022-7-4

I have write this function

function BESSsize = Bsize(x,y,z)
if 0.8*z >=x+y
Bsize=(x+y)*0.8/365
elseif  0.5*x+y<= z <0.8*x+y
Bsize=z/365
else
disp("Bad sizing")
end

It dosent run here but I saved in matlab and it works in my scripts.My problem is that if i try for example to multiply and use the result for example A=Bsize(10,50,100)*365 i obtain this error:

>> Bsize(10,50,100)

Bsize =

0.1315

>> A=Bsize(10,50,100)*365

Bsize =

0.1315

Output argument "BESSsize" (and possibly others) not assigned a value in the execution with "Bsize" function.

How can i solve this?

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Answer 1

Raghav 2022-7-4

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Hi @Pietro Fiondella

In the function definition:

function BESSsize = Bsize(x,y,z)

'BESSsize' is the variable which will be returned after function execution and the 'Bsize' is the function name.

You are assigning return value to 'Bsize', instead assign them to the returning variable 'BESSsize'.

So assign in the following way:

BESSsize=(x+y)*0.8/365;

and

BESSsize=z/365;

Also use ; if you do not want an output from statement in which you are assigning values.

One more thing is you are using

0.5*x+y<= z <0.8*x+y

which is of the form (a<=b)<c

I think it would be better to write in the form (a<=b) && (b<c) like:

((0.5*x+y)<=z) && (z<(0.8*x+y))

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Answer 2

Siraj 2022-7-4

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https://ww2.mathworks.cn/matlabcentral/answers/1752990-problem-with-custom-function#answer_999525

编辑：Siraj 2022-7-4

在 MATLAB Online 中打开

Hi,

It is my understanding that you are confusing between the function name “Bsize” and the variable “BESSsize” which is to be returned by the function.

In the if and elseif part you are creating a variable “Bsize” with the same name of the function and the output variable that you declared to be “BESSsize” is not being assigned any value. Therefore, you are seeing the error.

The solution is to change the “Bsize” to “BESSsize” in the "if" and "else if" part and also assign a value to "BESSsize" for the else part.

Refer to the documentation for more on functions in MATLAB.

A=Bsize(10,50,100)*365
A = 48.0000
function BESSsize = Bsize(x,y,z)
if 0.8*z >=x+y
    BESSsize = (x+y)*0.8/365;
elseif  0.5*x+y<= z <0.8*x+y
    BESSsize = z/365;
else
    disp("Bad sizing");
    BESSsize = 0;
end
end