Hello group,
am I doing something wrong or is the following a bug?
In [99]: limit(sqrt(x^2 + x +1) + x, x = -oo)
In [101]: limit(sqrt(x^2 + x +1) + x, x = -oo)
---------------------------------------------------------------------------
<type 'exceptions.TypeError'> Traceback (most recent call last)
/home/nea/<ipython console> in <module>()
[...] (snip)
<type 'exceptions.TypeError'>: Computation failed since Maxima requested
additional constraints (use assume):
Is x positive or negative?
In [100]: assume(x < 0)
In [101]: limit(sqrt(x^2 + x +1) + x, x = -oo)
---------------------------------------------------------------------------
<type 'exceptions.TypeError'> Traceback (most recent call last)
/home/nea/<ipython console> in <module>()
[...] (snip exactly the same stuff as before)
<type 'exceptions.TypeError'>: Computation failed since Maxima requested
additional constraints (use assume):
Is x positive or negative?
In [102]: sqrt(x^2)
Out[102]: -x
In [103]: forget()
In [104]: sqrt(x^2)
Out[104]: abs(x)
So it seems that the (redundant anyway) assumption that x < 0 is in
place, but it is not passed to the limit calculation. For
comparison the same limit with maxima:
(%i22) limit(sqrt(x^2 + x +1) + x, x, minf);
Is x positive or negative?
pos;
1
(%o22) - -
2
(%i23) limit(sqrt(x^2 + x +1) + x, x, minf);
Is x positive or negative?
neg;
(%o23) minf
which is wrong, but at least is an answer.
Best,
Nikos
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