[SciPy-user] optimize.fmin_l_bfgs_b problem

[Marek Wojciechowski]

Nils Wagner wrote:

> On Wed, 11 Jun 2008 22:00:05 +0200
>   Marek Wojciechowski <mwojc at p.lodz.pl> wrote:
>> Nils Wagner wrote:
>> 
>>> On Mon, 9 Jun 2008 15:50:53 +0200
>>>   Marek Wojciechowski <mwojc at p.lodz.pl> wrote:
>>>> Hi!
>>>> The following command:
>>>>    optimize.fmin_l_bfgs_b(lambda x: x[0]**2, [-1.],
>>>>iprint=1)
>>>> causes an error and breaks the python session with the
>>>>following output:
>>>> 
>>>> RUNNING THE L-BFGS-B CODE
>>>> 
>>>>           * * *
>>>> 
>>>> At line 2647 of file scipy/optimize/lbfgsb/routines.f
>>>> Internal Error: printf is broken
>>>> Machine precision =
>>>> 
>>>> This occurs on scipy-0.6.0 and python 2.4 under Gentoo
>>>>Linux. Is this the
>>>> known bug?
>>>> 
>>>> Greetings,
>>>> --
>>>> Marek Wojciechowski
>>> 
>>> I get
>>> 
>>>>>> optimize.fmin_l_bfgs_b(lambda x: x[0]**2, [-1.],
>>>>>>iprint=1)
>>> RUNNING THE L-BFGS-B CODE
>>> 
>>>             * * *
>>> 
>>> Machine precision = 2.220E-16
>>>   N =  1    M =  10
>>>   This problem is unconstrained.
>>> 
>>> At X0         0 variables are exactly at the bounds
>>> Traceback (most recent call last):
>>>    File "<stdin>", line 1, in <module>
>>>    File
>>> "/data/home/nwagner/local/lib/python2.5/site-packages/scipy/optimize/lbfgsb.py",
>>> line 205, in fmin_l_bfgs_b
>>>      f, g = func_and_grad(x)
>>>    File
>>> "/data/home/nwagner/local/lib/python2.5/site-packages/scipy/optimize/lbfgsb.py",
>>> line 156, in func_and_grad
>>>      f, g = func(x, *args)
>>> TypeError: 'numpy.float64' object is not iterable
>>> 
>>>>>> scipy.__version__
>>> '0.7.0.dev4420'
>> 
>> It seems that my bug is corrected in development
>>versions of scipy.
>> Exception you obtained results probably from new layout
>>of lbfgsb
>> optimizer. I think the following should work:
>> 
>> optimize.fmin_l_bfgs_b(lambda x: (x[0]**2, 2*x[0]),
>>[-1.], iprint=1)
>> 
> No.
>>>> optimize.fmin_l_bfgs_b(lambda x: (x[0]**2, 2*x[0]), [-1.], iprint=1)
> RUNNING THE L-BFGS-B CODE
> 
>             * * *
> 
> Machine precision = 2.220E-16
>   N =  1    M =  10
>   This problem is unconstrained.
> 
> At X0         0 variables are exactly at the bounds
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File
> "/usr/local/lib64/python2.5/site-packages/scipy/optimize/lbfgsb.py",
> line 199, in fmin_l_bfgs_b
>      isave, dsave)
> TypeError: failed to initialize
> intent(inout|inplace|cache) array -- input must be array
> but got <type 'numpy.float64'>
>   
> Cheers,
>             Nils

The last chance :) :
optimize.fmin_l_bfgs_b(lambda x: (x[0]**2, 2*x[0]), array([-1.]), iprint=1)

-- 
Marek Wojciechowski