Symbolic Integration
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Hi everybody,
I have a little question about 'int' function. I have this code:
>> syms x y
>> int(x+y,x)
so I want to know why is this the result?:
ans =
(x + y)^2/2
instead of:
x^2/2+x*y
I'm a little confused about it, I hope you can help me understand.
采纳的回答
Teja Muppirala
2011-3-12
Both answers are correct.
d/dx[ (x+y)^2/2 ] = d/dx[ x^2/2 + x*y + y^2/2 ] = x + y
d/dx[ x^2/2 + x*y ] = x + y
The ambiguity lies in the constant of integration. In the first case the constant of integration ends up being y^2/2.
If you really want to enforce that the constant of integration is zero then do:
F = int(x+y,x,0,x)
expand(F)
更多回答（1 个）
Walter Roberson
2011-3-12
0 个投票
Odd, I don't get that in Maple; unfortunately I don't have the Symbolic Toolbox to test with.
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