Can someone confirm my differentiation code is correct?

Question

Ruslan Khoguev 2019-9-8

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回答： Devineni Aslesha 2019-9-11

I need to differentiate P(a,u,EA1,EA2) with respect to u. I get the code to run, but im not sure the answer is correct since it gives me a long answer.

syms L10(a) L1(a,u) epsilon1(a,u) L20(a) N1(a,u,EA1) N2(a,u,EA2) P(a,u,EA1,EA2)
L10(a) = 2*a;
L20(a) = sqrt(5)*a;
L1(a,u) = sqrt((2*a)^2+u^2);
L2(a,u) = sqrt((2*a)^2+(a-u)^2);
epsilon1(a,u) = (L1(a,u)-L10(a))/L10(a);
epsilon2(a,u) = (L2(a,u)-L20(a))/L20(a);
N1(a,u,EA1) = EA1*epsilon1(a,u);
N2(a,u,EA2) = EA2*epsilon2(a,u);
P(a,u,EA1,EA2) = (u/(L1(a,u)))*(N1(a,u,EA1))-((a*u)/(L2(a,u)))*(N2(a,u,EA2));
df = diff(P(a,u,EA1,EA2),u)

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Ruslan Khoguev 2019-9-9

I meant does the code make sense? Am I differentiating P(a,u,EA1,EA2) with respect to u correctly?

Walter Roberson 2019-9-9

Yes, that is correct syntax for differentiating the expression returned by P(a,u,EA1,EA2) with respect to u.

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Answer 1

Devineni Aslesha 2019-9-11

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/479397-can-someone-confirm-my-differentiation-code-is-correct#answer_391329

The code written to differentiate P (a, u, EA1, EA2) with respect to u is correct. It will give correct result. The reason for the answer to be long might be because of the display of all the terms in the differentiated output.