??? Index exceeds matrix dimensions.

Question

MinHyung 2013-8-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/85154-index-exceeds-matrix-dimensions

I tried to use function 'quad' but failed...

>> quad (@(phi) (224 - 32*sin(7) + 32*cos((7.*cos(phi))./2).^2.*sin(7) + 32*cos((7.*sin(phi))./2).^2.*sin(7) - 224*cos((7*cos(phi))./2).^2 - 224*cos((7*sin(phi))./2).^2 - 32*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2.*sin(7) + 224*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2)/(823543.*cos(phi).^2 - 823543*cos(phi).^4), 0.1,pi/2-0.1)
 ??? Index exceeds matrix dimensions.
Error in ==> quad at 85
if ~isfinite(y(7))

--------------------------------------------------------------------

'quad' with separate part works well

this part :

(224 - 32*sin(7) + 32*cos((7.*cos(phi))./2).^2.*sin(7) + 32*cos((7.*sin(phi))./2).^2.*sin(7) - 224*cos((7*cos(phi))./2).^2 - 224*cos((7*sin(phi))./2).^2 - 32*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2.*sin(7) + 224*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2)

and this part :

(823543.*cos(phi).^2 - 823543*cos(phi).^4

Is there anyone who knows this reason?

Thank you very much in advance.

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Answer 1

the cyclist 2013-8-20

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编辑：the cyclist 2013-8-20

在 MATLAB Online 中打开

Do you get what you expect if you use "./" instead of just "/" for the division of your two terms?

This code works for me:

f1 = @(phi) (823543.*cos(phi).^2 - 823543*cos(phi).^4);
f2 = @(phi) (224 - 32*sin(7) + 32*cos((7.*cos(phi))./2).^2.*sin(7) + 32*cos((7.*sin(phi))./2).^2.*sin(7) - 224*cos((7*cos(phi))./2).^2 - 224*cos((7*sin(phi))./2).^2 - 32*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2.*sin(7) + 224*cos((7*cos(phi))./2).^2.*cos((7*sin(phi))./2).^2);
f3 = @(phi) f2(phi)./f1(phi);
quad(f3,0.1,pi/2-0.1)