在 Maple 中执行从负无穷大到无穷大的积分
我正在尝试在 Maple 中执行以下积分:
simplify(int(a*x^2*e^(-a*x^2), x = -infinity .. infinity))
但 Maple 不返回答案,而是返回积分语句本身:
int(a*x^2*e^(-a*x^2), x = -infinity .. infinity)
不过以更漂亮的形式(带有实际的积分符号等)。我尝试删除“simplify()”,但没有任何区别。
知道为什么吗?它应该返回一个值。
I'm trying to perform the following integral in Maple:
simplify(int(a*x^2*e^(-a*x^2), x = -infinity .. infinity))
But instead of returning an answer, Maple just returns back the integral statement itself:
int(a*x^2*e^(-a*x^2), x = -infinity .. infinity)
In the prettier form though (with the actual integral sign, etc). I've tried removing the "simplify()" but it doesn't make any difference.
Any idea why that is? It should return a value.
如果你对这篇内容有疑问,欢迎到本站社区发帖提问 参与讨论,获取更多帮助,或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱,如果其他用户或者作者回复了您的评论,将不能在第一时间通知您!
发布评论
评论(3)
您可能只是遇到语法问题。应用于 x 的指数函数是 exp(x) 而不是 e^x。
You may have just a syntax problem. The exponential function applied to x is exp(x) not e^x.
你必须告诉 maple
a
有正实部。否则,积分不存在。请参阅手册了解如何执行此操作。IIRC,有一个
assume
函数和一个symbolic
选项,您可以传递给各种函数(包括 Simply 和 int)。You have to tell maple that
a
has positive real part. Otherwise, the integral does not exist. Consult the manual for how to do this.IIRC, there is a
assume
function, and asymbolic
option you can pass to various functions (including simplify and int).对于它的价值 Wolfram Alpha 似乎能够做到这一点:
它给出的答案为
sqrt(pi ) / (2 * sqrt (a))
(假设Re(a) > 0
)。For what it's worth Wolfram Alpha seems to be able to do this:
It gives an answer of
sqrt(pi) / (2 * sqrt (a))
(assumingRe(a) > 0
).