How to fix errors within double integral.

Question

Amanda 2022-10-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1839088-how-to-fix-errors-within-double-integral

回答： Carlos Guerrero García 2022-11-26

采纳的回答： Paul

在 MATLAB Online 中打开

I need to graph the region. This is the code I started with

fun = @(x,y) 5
xmin = -3
xmax= 3
ymin = @(x) -1.*sqrt(9- x.^2)
ymax = @(x) sqrt(9- x.^2);
q = integral2(fun,xmin,xmax,ymin,ymax)

Whenever I try to run this I get several error meassages.

Error using integral2Calc>integral2t/tensor (line 241)
Integrand output size does not match the input size.
Error in integral2Calc>integral2t (line 55)
[Qsub,esub] = tensor(thetaL,thetaR,phiB,phiT);
Error in integral2Calc (line 9)
[q,errbnd] =
integral2t(fun,xmin,xmax,ymin,ymax,optionstruct);
Error in integral2 (line 105)
Q =
integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct);
Error in math241_project2 (line 7)
q = integral2(fun,xmin,xmax,ymin,ymax)

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Answer 1

Paul 2022-10-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1839088-how-to-fix-errors-within-double-integral#answer_1087133

编辑：Paul 2022-10-30

在 MATLAB Online 中打开

Hi @Amanda,

The doc page for integral2 say that the function that defines the integrand "must accept two arrays of the same size and return an array of corresponding values." However, fun in the Question always returns a scalar for any pair of inputs. Correct fun as shown below so it returns an array the same size as x with all elements equal to 5

fun = @(x,y) 5*ones(size(x));
xmin = -3;
xmax = 3;
ymin = @(x) -1.*sqrt(9 - x.^2);
ymax = @(x)     sqrt(9 - x.^2);
q = integral2(fun,xmin,xmax,ymin,ymax)
q = 141.3717