An UndefinedFunction error thrown by parfor but not for

Question

Leos Pohl 2021-6-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/852280-an-undefinedfunction-error-thrown-by-parfor-but-not-for

回答： Jan 2021-6-9

采纳的回答： Jan

在 MATLAB Online 中打开

I have a script 'load_constants.m' that has:

a = 1737400.0;

main program:

load_constants
el = fce();

and the called function is defined:

function el = fce()
    load_constants
    parfor i = 1:n
        alpha = fce2(a)
    end

When i run it, i get

Error using fce (line 50)

An UndefinedFunction error was thrown on the workers for 'a'.  This might be because the file containing 'a' is not accessible on the workers.  Use addAttachedFiles(pool, files) to specify the required files to be attached.  For more information see the documentation for 'parallel.Pool/addAttachedFiles'.
Error in run (line 3)
el = fce();
Caused by:
    Undefined function or variable 'a'.

When I change the loop to for loop, all works fine.

What is the issue?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jan 2021-6-9

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/852280-an-undefinedfunction-error-thrown-by-parfor-but-not-for#answer_721110

在 MATLAB Online 中打开

Constants defined in scripts cannot be identified by the Matlab, when it parses the parfor block. In addition such scripts have a bunch of further disadvantages also. A good programming practice is to avoid scripts consequently. Use functions instead:

function el = fce()
    C = load_constants();
    parfor i = 1:n
        alpha = fce2(C.a);
    end
end
function C = load_constants()
C.a = 1737400.0;
end