Strange Mathematica behavior

So far so good. This is the correct result. Now multiply the x by 1.0:


That makes Mathematica think that the integral fails to converge.

I found this out when reproducing some calculations from a couple of years ago. It seemed to work back then, so this behavior seems to have been introduced in a recent version of Mathematica.

I know of various reasons why putting in the 1.0 could make a difference (because it forces Mathematica to think in terms of floating-point numbers with finite accuracy, rather than exact integers), but I don’t think any of them should make a difference here. The integral is failing to converge at x=0 (I checked that the problem is there, not at infinity), and the integrand is perfectly well-behaved there, even if you replace the 1.0 by any other complex number.


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Ted Bunn

I am chair of the physics department at the University of Richmond. In addition to teaching a variety of undergraduate physics courses, I work on a variety of research projects in cosmology, the study of the origin, structure, and evolution of the Universe. University of Richmond undergraduates are involved in all aspects of this research. If you want to know more about my research, ask me!