[sage-support] Re: A genuine bug in numerical evaluation ?

2019-06-06 Thread John H Palmieri 
Oh, and Sage with Python 3 is in pretty good shape these days. Still some 
doctest failures, but I think it is mostly very functional.

  John


On Thursday, June 6, 2019 at 3:20:25 PM UTC-7, John H Palmieri wrote:
>
> I can confirm that it works for me on OS X with Python 3, gives the error 
> you described with Python 2.
>
>
> On Thursday, June 6, 2019 at 2:57:08 PM UTC-7, Emmanuel Charpentier wrote:
>>
>> According to Serge Lelièvre, the proble doesn't occur when ran under a 
>> Python3-based Sage. He advises to run such a Sage, hich seems a bit early, 
>> IMHO?
>>
>> Advice ?
>>
>>
>> Le jeudi 6 juin 2019 11:04:27 UTC+2, Emmanuel Charpentier a écrit :
>>>
>>> This ask.sagemath  question 
>>> 
>>>  seems 
>>> to raise a genuine bug. Perusing Trac doesn't raise muc relevant, possibly 
>>> except for Trac#24428  and 
>>> Trac#21754 .
>>>
>>> From my comment to the ask.sagemath question :
>>>
>>> Indeed :
>>> sage: var("y,z")
>>> (y, z)
>>> sage: cauchy(z)=solve(z*y^3 +y^2 - 2*z*y+2 ,y)[0].rhs()
>>> sage: def foo(u):return(arg(cauchy(u)).n())
>>> sage: [foo(t) for t in (1,1.1..2)]
>>> [0.828222717321238,
>>> ## Snip...
>>>  0.377665318352514]
>>> Therefore, this function *can* be evaluated. But :
>>> sage: plot(foo,(1,2))
>>> verbose 0 (3635: plot.py, generate_plot_points) WARNING: When 
>>> plotting, failed to evaluate function at 200 points.
>>> verbose 0 (3635: plot.py, generate_plot_points) Last error message: 
>>> 'negative number cannot be raised to a fractional power'
>>> Launched png viewer for Graphics object consisting of 0 graphics 
>>> primitives
>>> ... not in `plot`. Trying  to plot symbolically yelds :
>>> TypeError: Cannot evaluate symbolic expression to a numeric value.
>>> A bug, IMHO.
>>>
>>> Can someone confirm this and, possibly, give me hints as how to flag 
>>> this ticket efficiently ?
>>>
>>

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[sage-support] Re: A genuine bug in numerical evaluation ?

2019-06-06 Thread John H Palmieri 
I can confirm that it works for me on OS X with Python 3, gives the error 
you described with Python 2.


On Thursday, June 6, 2019 at 2:57:08 PM UTC-7, Emmanuel Charpentier wrote:
>
> According to Serge Lelièvre, the proble doesn't occur when ran under a 
> Python3-based Sage. He advises to run such a Sage, hich seems a bit early, 
> IMHO?
>
> Advice ?
>
>
> Le jeudi 6 juin 2019 11:04:27 UTC+2, Emmanuel Charpentier a écrit :
>>
>> This ask.sagemath  question 
>> 
>>  seems 
>> to raise a genuine bug. Perusing Trac doesn't raise muc relevant, possibly 
>> except for Trac#24428  and 
>> Trac#21754 .
>>
>> From my comment to the ask.sagemath question :
>>
>> Indeed :
>> sage: var("y,z")
>> (y, z)
>> sage: cauchy(z)=solve(z*y^3 +y^2 - 2*z*y+2 ,y)[0].rhs()
>> sage: def foo(u):return(arg(cauchy(u)).n())
>> sage: [foo(t) for t in (1,1.1..2)]
>> [0.828222717321238,
>> ## Snip...
>>  0.377665318352514]
>> Therefore, this function *can* be evaluated. But :
>> sage: plot(foo,(1,2))
>> verbose 0 (3635: plot.py, generate_plot_points) WARNING: When 
>> plotting, failed to evaluate function at 200 points.
>> verbose 0 (3635: plot.py, generate_plot_points) Last error message: 
>> 'negative number cannot be raised to a fractional power'
>> Launched png viewer for Graphics object consisting of 0 graphics 
>> primitives
>> ... not in `plot`. Trying  to plot symbolically yelds :
>> TypeError: Cannot evaluate symbolic expression to a numeric value.
>> A bug, IMHO.
>>
>> Can someone confirm this and, possibly, give me hints as how to flag this 
>> ticket efficiently ?
>>
>

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[sage-support] Re: A genuine bug in numerical evaluation ?

2019-06-06 Thread Emmanuel Charpentier 
According to Serge Lelièvre, the proble doesn't occur when ran under a 
Python3-based Sage. He advises to run such a Sage, hich seems a bit early, 
IMHO?

Advice ?


Le jeudi 6 juin 2019 11:04:27 UTC+2, Emmanuel Charpentier a écrit :
>
> This ask.sagemath  question 
> 
>  seems 
> to raise a genuine bug. Perusing Trac doesn't raise muc relevant, possibly 
> except for Trac#24428  and 
> Trac#21754 .
>
> From my comment to the ask.sagemath question :
>
> Indeed :
> sage: var("y,z")
> (y, z)
> sage: cauchy(z)=solve(z*y^3 +y^2 - 2*z*y+2 ,y)[0].rhs()
> sage: def foo(u):return(arg(cauchy(u)).n())
> sage: [foo(t) for t in (1,1.1..2)]
> [0.828222717321238,
> ## Snip...
>  0.377665318352514]
> Therefore, this function *can* be evaluated. But :
> sage: plot(foo,(1,2))
> verbose 0 (3635: plot.py, generate_plot_points) WARNING: When 
> plotting, failed to evaluate function at 200 points.
> verbose 0 (3635: plot.py, generate_plot_points) Last error message: 
> 'negative number cannot be raised to a fractional power'
> Launched png viewer for Graphics object consisting of 0 graphics 
> primitives
> ... not in `plot`. Trying  to plot symbolically yelds :
> TypeError: Cannot evaluate symbolic expression to a numeric value.
> A bug, IMHO.
>
> Can someone confirm this and, possibly, give me hints as how to flag this 
> ticket efficiently ?
>

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