syms x f(x) = cos(x)*sin(x); Fx = int(f,x) Fx(x) = sin(x)^2/2 while the correct answer is -cos(x)^2/2

Int gives wrong answer

Ali M

2022 3 2

1 个回答

17 次查看（30 天）

0 个投票

syms x

f(x) = cos(x)*sin(x);

Fx = int(f,x)

Fx(x) =

sin(x)^2/2

while the correct answer is -cos(x)^2/2

3 个评论
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Torsten 2022-3-2

Since sin(x)^2/2 = -cos(x)^2/2 + 1/2, both answers are correct.

Note that both answers only differ by a constant, namely 1/2.

Ali M 2022-3-5

Thanks @Torsten & @Robin Merkle! @Torsten I would vote for you but I cant, your is a comment not an answer

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回答（1 个）

Walter Roberson 2022-3-2

0 个投票

Remember that indefinite integration always has an implied "plus a constant". So any two results of int() that differ by a constant are the same integral result. And sin squared plus cos squared equals 1 so the two possibilities are the same up to the constant.

You can ask to rewrite() to 'cos'