Integration using quad(@myfun,a,b)

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Amy 2014-4-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/124460-integration-using-quad-myfun-a-b

评论： Star Strider 2014-4-5

采纳的回答： Star Strider

在 MATLAB Online 中打开

I have the following function

    function AW1= AW_int()
    ASqr=aSqrSum();
    BSqr=bSqrSum();
    C=CSum();
    delta2=(ASqr.*BSqr)-(C.^2);
    delta=delta2.^(1/2);
    AW1=delta./ASqr;
    format long e
    delta2;
    delta;
    %delta2; delta; 
    AW1;
    end

Using the following functions for ASqr, BSqr and C

    function ASqr =aSqrSum(x,N)
N=[1000 10000 100000];
x=[0.9 0.99 0.999 0.9999];
ASqr = zeros(length(N), length(x));
for ii = 1:length(N)
    for n = 0:N(ii)-1
       ASqr(ii,:) = ASqr(ii,:) + (x.^(2*n));
    end
end
    function C = CSum(x,N)
N=[1000 10000 100000];
x=[0.9 0.99 0.999 0.9999];
C = zeros(length(N), length(x));
for ii = 1:length(N)
    for n = 0:N(ii)-1
       C(ii,:) = C(ii,:) + (n.*x.^(2.*(n)-1)) ;
    end
end
format long e
C;
end
format long e
ASqr;
end
    function BSqr =bSqrSum(x,N)
N=[1000 10000 100000];
x=[0.9 0.99 0.999 0.9999];
BSqr = zeros(length(N), length(x));
for ii = 1:length(N)
    for n = 0:N(ii)-1
       BSqr(ii,:) = BSqr(ii,:) + ((n.^2).*x.^(2.*(n)-2));
    end
end
format long e
BSqr;
end

When i try to integrate the function AW_int using

Q = quad(@AW_int,0,0.9999)

The following error is returned:

    Error using AW_int
Too many input arguments.
   Error in quad (line 72)
y = f(x, varargin{:});

Would anyone be able to help me fix this? As I have tried a few different things but the same error is still be returned.

Thanks

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Star Strider 2014-4-4

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/124460-integration-using-quad-myfun-a-b#answer_132211

在 MATLAB Online 中打开

Your AW_int function doesn’t take any input arguments:

function AW1= AW_int()

Also, you are not passing any arguments to these functions within AW_int, so they will likely throw a similar error when AW_int executes:

    ASqr=aSqrSum();
    BSqr=bSqrSum();
    C=CSum();

They all require x and N as inputs, so pass those to AW_int and then to the other functions.

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Amy 2014-4-5

Mathwork2.pdf

Sorry.. hope this helps

Star Strider 2014-4-5

在 MATLAB Online 中打开

Definitely helps, but I’m a bit baffled by the implied recursion. You calculate

∆² = A²B²-C²

all of which are functions of x, and with

A² = ∑x²ʲ

then go back and integrate ∆/A² w.r.t. x.

Also, when I calculate (with EN the asymptotic expression), I get:

Q/(EN*pi) = 1.2031 1.3860 1.2943

perhaps accounted for by σ² not appearing anywhere, but just a guess on my part.

If there’s no recursion, and you treat ∆/A² essentially as a constant, then you pretty much have calculated Q about as well as can be expected, except for dividing it by pi. I am not convinced that using continuous functions and integrate would be of any significant benefit.

If there is recursion, then it seems to me you carry out the summations and calculate ∆/A² for each x(j), integrate from a to b, and repeat until you reach j=(n-1). Maybe I’m missing something.

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