how to use command"matlabFunction" in loop and handle function in loop

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tony kevine 2015-4-17

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评论： Star Strider 2015-4-20

syms x y
rr=[x^2+y^2,x^2+1,y^2+2,3*x^3;
     y^7+2,x^2+y,x^4+y^7,2]
for i=1:8
     f(i)=matlabFunction(rr(i))
     ma(i)=dblquad(f(i),-1,1,-1,1)
end

Can anyone help!! i really need help!! Above is my code!! my aim is to double integral(dblquad) the code have error when i run it .can any help me to modify it!! rr is my assumption.ecactly rr is big so i use a small matrix to replace

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tony kevine 2015-4-20

i have another question. how to look up a command which version release?

Star Strider 2015-4-20

Go to the MATLAB Index and search for the function. The approximate release when it first appeared is at the end of the documentation page for it. That is new with the documentation for the R2015a release that is the current online documentation.

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Answer 1

Star Strider 2015-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/209613-how-to-use-command-matlabfunction-in-loop-and-handle-function-in-loop#answer_175649

在 MATLAB Online 中打开

It’s best not to bother with the numeric integrations and just keep it symbolic:

syms x y
rr=[x^2+y^2,x^2+1,y^2+2,3*x^3;
     y^7+2,x^2+y,x^4+y^7,2]
ma_x = int(rr, x, -1, 1);
ma   = int(ma_x, y, -1, 1)

produces:

ma =
[ 8/3, 16/3, 28/3, 0]
[   8,  4/3,  4/5, 8]

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tony kevine 2015-4-17

dear Star Strider.

above rr is sample matrix ,exactly my matrix is so big and it need to numerically method to solve it.thanks you answer my issue

Star Strider 2015-4-17

My pleasure.

Have you tried this on your much larger matrix?

I attempted a number of numerical integration routines (including those available in R2015a, such as integral with the 'ArrayValued',1 option) and I could not get it to run without throwing an error.

The only other option I can think of is to integrate each element of your matrix separately, creating a separate anonymous function for each element.

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Answer 2

Sean de Wolski 2015-4-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/209613-how-to-use-command-matlabfunction-in-loop-and-handle-function-in-loop#answer_175650

在 MATLAB Online 中打开

Use cells to store the function handles

syms x y
rr=[x^2+y^2,x^2+1,y^2+2,3*x^3;
   y^7+2,x^2+y,x^4+y^7,2]
f = cell(8,1)
for i=1:8
   f{i}=matlabFunction(rr(i))
   ma(i)=dblquad(f{i},-1,1,-1,1)
end

This won't fix the fact that your functions need different inputs so you'll need to figure that out.

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tony kevine 2015-4-17

hi,why need more inputs.actualy my real matrix is so big .above is my assumption i just ran your code,and it occur error.can you explain again(i am asian so please use some simple words)

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