# SageMath crashes when doing simple function arithmetics

Hello,

I'm trying to run the following code which computes a simple rational function.

d = 4
p = (d+2)/(d-2)
W(r) = (1+r^2/(d*(d-2)))^(-(d-2)/2)
print(p*W(r)^(p-1))


This code works fine in "sagecell dot sagemath dot org" (it takes only a few seconds). But if I run it on my SageMath terminal (which I've installed yesterday, so it's up-to-date), I get : ' /usr/share/sagemath/bin/sage-python : ligne 2 : 3988 Processus arrêté sage -python "\$@" '

The code works fine in my SageMath terminal if I replace d by d = 3, d = 5, d = 6 or even d = 100. I've identified that the problem is due to p = (d+2)/(d-2). When d = 4, if I replace p = (d+2)/(d-2) by p = 3 or p = RR((d+2)/(d-2)), it works. But I don't understand why it does not work otherwise ?

EDIT :

This code was run on Ubuntu 20.04.3 (from Windows 10 using VirtualBox). SageMath 9.0 was installed using the command "sudo apt-get install sagemath". I didn't know this would not install the latest version. I'll try to update SageMath first and then we'll see.

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Could you please give us some informations so that someone can try to reproduce your problem:

• which version of Sage did you use ?
• which OS ?
• did you install Sage from the distribution, and which package ?
• did you install Sage from the binaries, and which ones ?
• did you compile Sage yourself ?
• ... ?
( 2021-10-08 10:53:54 +0200 )edit

sagemath 9.2 is not up to date at all ! La version 9.4 est sortie récemment.

( 2021-10-08 11:43:52 +0200 )edit

@tmonteil@FrédéricC I've updated my post. You're right, my SageMath is not up to date. I thought that the sudo apt-get install command would install the latest version. I'll try to update first and then I'll come back.

( 2021-10-08 12:28:08 +0200 )edit