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zest1979

银虫 (小有名气)

[求助] 求助,万分感谢

求如下函数对s的积分:0.5*epsi2.*((1+s*epsi2).^2.*(1+s*epsi1)).^-0.5*1./(1+s*epsi2),积分区间在0到无穷之间。
epsi1和epsi2是一个和s无关的量。
我自己用matlab试过了,提示为:Explicit integral could not be found。有哪位大侠能帮忙一下
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zest1979

银虫 (小有名气)

没人能指导一下吗
2楼2013-04-25 12:56:04
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phykid

木虫 (正式写手)

以下内容来自matlab说明文档:


If int cannot compute a closed form of anintegral, it issues a warning and returns an unresolved integral:
syms x
F = sin(sinh(x));
int(F, x)Warning: Explicit integral could not be found.

ans =
int(sin(sinh(x)), x)
If int cannot compute a closed form of anindefinite integral, try to approximate the expression around somepoint using taylor, and thencompute the integral. For example, approximate the expression around x =0:
int(taylor(F, x, 'ExpansionPoint', 0, 'Order', 10), x)ans =
x^10/56700 - x^8/720 - x^6/90 + x^2/2


Compute this definite integral:
syms x
F = int(cos(x)/sqrt(1 + x^2), x, 0, 10)Warning: Explicit integral could not be found.

F =
int(cos(x)/(x^2 + 1)^(1/2), x == 0..10)
If int cannot compute a closed form of adefinite integral, try approximating that integral numerically using vpa. For example, approximate F with5 significant digits:
vpa(F, 5)ans =
0.37571
3楼2013-04-26 10:09:10
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