Recall workspace variable in a function

Question

Carlo Alberto Carissimi 2018-12-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/433709-recall-workspace-variable-in-a-function

评论： Stephen23 2018-12-4

Hi there!

I'm in trouble with this matlab function that i wrote.

function write_txt(filename)
Title_1 = 'Results';
Label_1 = '     Value1   ';
Label_2 = '     Value2   ';
Label_3 = '     Value3   '; 
Mo_1 = {'Results'};
Data_1 = [x y z];
fid = fopen(filename,'w+t'); 
if fid < 0
    fprintf('error opening file\n');
    return;
end
fprintf(fid,'%s\n',Title_1);
fprintf(fid,'\n'); 
fprintf(fid,'      %s%s%s\n',Label_1,Label_2,Label_3);
for ii= 1:1
    fprintf(fid,'%5s: ',Mo_1{ii});
    fprintf(fid,'%5.2f,%5.2f\n',Data_1(ii,:));
end
fclose(fid);
end

Basically this function write a .txt with all my results from another matlab script. The variable calculted in another matlab script (x,y,z) should be write on the txt file.

When i try to make the .txt file through the Command Window, Matlab give me this error:

Undefined function or variable 'x'.
Error in write_txt (line 7)
Data_1 = [x y z];

While the x,y,z variables are defined. Someone can help me?

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Carlo Alberto Carissimi 2018-12-4

在 MATLAB Online 中打开

Hi! I tried, gave me this:

>> write_txt
Not enough input arguments.
Error in write_txt (line 7)
Data_1 = [x 2 3];

Stephen23 2018-12-4

@Carlo Alberto Carissimi: you need to provide the required input arguments when you call the function, e.g.:

>> write_txt('myfile.txt',1,5,23)

How to call functions is a very basic MATLAB concept that is explained in the introductory tutorials:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

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Answer 1

madhan ravi 2018-12-4

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https://ww2.mathworks.cn/matlabcentral/answers/433709-recall-workspace-variable-in-a-function#answer_350424

编辑：madhan ravi 2018-12-4

Define x y z before using it? Because matlab won't show that error if the variables are in workspace already.

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Carlo Alberto Carissimi 2018-12-4

>> whos x

Name Size Bytes Class Attributes

x 1x1 8 double

madhan ravi 2018-12-4

so why not just define it inside the function since it's a scalar?

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Answer 2

Walter Roberson 2018-12-4

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https://ww2.mathworks.cn/matlabcentral/answers/433709-recall-workspace-variable-in-a-function#answer_350427

the variables are not define in the workspace active in the function .They might possibly be in the base workspace and if so could be pulled from there if really needed . but better would be if you pass their values to the function as additional arguments.