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talkquan

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xiemingya

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csgt0: 金币+1, 谢谢 2013-07-24 17:04:00
当求定积分时,出现的是式子,输入double(fx1)即可求出定积分的值。
matlab积分计算
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5楼2013-07-24 14:06:24
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dbb627

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【答案】应助回帖

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感谢参与,应助指数 +1
talkquan: 金币+10, ★★★★★最佳答案, 谢谢了! 2013-07-23 18:30:58
csgt0: 金币+2, 多谢指导 2013-07-24 17:03:22
>> syms x
>> fx=(3*pi)^0.5*(6*x^2-1)*exp(-3*x^2);%fx为被积分函数%
>> fx1=int(fx,x,28.81,inf)

fx1 =

19916297312802753363/(225179981368524800*exp(24900483/10000)) + (2304326890293041*3^(1/2)*pi^(1/2)*erf((2881*3^(1/2))/100))/4503599627370496 + (2304326890293041*3^(1/2)*pi^(1/2)*erfi((2881*3^(1/2)*i)/100)*i)/4503599627370496

>> vpa(fx1,100)

ans =

0.0
The more you learn, the more you know, the more you know, and the more you forget. The more you forget, the less you know. So why bother to learn.
2楼2013-07-23 16:10:08
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talkquan

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3楼2013-07-23 16:33:38
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dbb627

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csgt0: 金币+1, 谢谢 2013-07-24 17:03:56
引用回帖:
3楼: Originally posted by talkquan at 2013-07-23 16:33:38
什么意思啊,matlab才学,不懂啊,麻烦解释下咯...

就是积分结果为0
erfi参见,我的matlab版本低没有定义这个函数,但是积分中却出现了很奇怪
http://www.mathworks.cn/cn/help/symbolic/erfi.html
The more you learn, the more you know, the more you know, and the more you forget. The more you forget, the less you know. So why bother to learn.
4楼2013-07-23 16:54:13
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