ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Mon, 14 Feb 2011 21:36:02 +0100Strange behviour when trying to integrate gaussian function. bug?https://ask.sagemath.org/question/7943/strange-behviour-when-trying-to-integrate-gaussian-function-bug/I was trying integrate the following function
y=var('y')
integrate(x*exp(-(x-y)*(x-y)*2.0),x)
$$\frac{1}{8} \, {\left(\frac{2 \, {\left(\text{erf}\left(\sqrt{2} \sqrt{{\left(x - y\right)}^{2}}\right) - 1\right)} {\left(x - y\right)} \sqrt{\pi} y}{\sqrt{{\left(x - y\right)}^{2}}} - \sqrt{2} e^{\left(-2 \, {\left(x - y\right)}^{2}\right)}\right)} \sqrt{2}$$
The integral can easily be done by redefining variables and does not have to be expressed in terms of error functions. Also the behavior of sage becomes even strange when I change the coefficient from 2.0 to 2.1. Sage just refuses to do the integral
integrate(x*exp(-(x-y)*(x-y)*2.1),x)
$$\int x e^{\left(-2.1 \, {\left(x - y\right)}^{2}\right)}\,{d x}$$
Any ideas on how to make sage give an answer in the usual exponential form?
Edit: Sorry. My bad. It is an error function. However, I expect error function even for the second example, when I replace 2 by 2.1. Any ideas why that is the case?
ShashankMon, 14 Feb 2011 21:36:02 +0100https://ask.sagemath.org/question/7943/