Sympy integration algorithm towards -infinity

Question

Following achrzesz hint about integral's algorithm option, I tried (Sage 4.7.2):

integral(1/x^2, x, -infinity, -1, algorithm='sympy')

Unfortunately, I got:

Traceback (click to the left of this block for traceback)
...
AttributeError: 'MinusInfinity' object has no attribute '_sympy_'

What's going wrong?

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Green diod has selected this answer as correct

It seems to be a bug. sympy can recognize infinity but not minus infinity of sage. You can try to directly call sympy integrate instead

import sympy as sp
a=sp.Symbol('a')
b=sp.integrate(1/x^2,(x,a,-1))._sage_()
b.substitute(a=-oo)

link

posted Jan 21 '12

Shashank

1570 ● 5 ● 22 ● 55

How do you get this infinity symbol? But most importantly, do you input this code in a simple python interpreter or in Sage? What is this _sage_() method?

Green diod (Jan 23 '12)

How do you get this infinity symbol?

Green diod (Jan 23 '12)

Every element from another program (such as sympy) has a _sage_ method to convert its things back to Sage objects. The infinity symbol is just one of the several ways to represent infinity in Sage (and several other programs of this type); in principle, it should be equivalent to using infinity, but apparently this bug leaves it to not work for Sympy.

kcrisman (Jan 23 '12)

All right, but how do you input the infinity symbol?

Green diod (Jan 23 '12)

1

-oo is just minus oo the alphabets

Shashank (Jan 23 '12)

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Answer 2

1	sage: from sympy import * sage: integrate(1/x^2, (x, -oo, -1), algorithm='sympy') 1 link posted Jan 21 '12 achrzesz 1661 ● 4 ● 16 ● 36 How do you get this infinity symbol?? Anyway, I still get the same error even at the console using -infinity Green diod (Jan 23 '12)

Sympy integration algorithm towards -infinity

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