Code segment I proposed should be changed as below. Otherwise it fails
when sqrt()'s are not involved.
def continued_fraction(a, b):
p = Wild('p')
q = Wild('q')
r = Wild('r')
a = Add(a)
match = a.match(p + r*sqrt(q))
# and do the processing according to whether
# q = 0 or not
On Fri, Jun 28, 2013 at 10:00 PM, Thilina Rathnayake <thilina.r...@gmail.com
> wrote:
> One approach would be to have three inputs to continued_fraction() function
> corresponding to the general form of a quadratic irrational fraction (a +
> sqrt(b)) / c
> We can set b = 0 for other cases. But I think it is not a good approach.
>
> Another approach would be to keep the current interface of
> continued_fraction()
> unchanged and pattern match to identify sqrt() s involved in the numerator.
>
> def continued_fraction(a, b):
> p = Wild('p')
> q = Wild('q')
> match = a.match(p + sqrt(q))
> # and do the processing according to whether
> # q = 0 or not
>
>
>
> On Fri, Jun 28, 2013 at 8:23 PM, Thilina Rathnayake <
> thilina.r...@gmail.com> wrote:
>
>> Yes, that is where it should go. I don't think it will be that hard to
>> combine.
>> There is a Java code <http://www.alpertron.com.ar/CONTFRAC.HTM> that is
>> used in Dario Alpern's website.
>>
>> I need the continued_fraction representation of quadratic irrational
>> numbers
>> in the Diophantine equation module. I can implement it in diophantine
>> module
>> but I think that does not belong there. We should implement it in ntheory
>> and then use it in Diophantine module. Shall I start on this?
>>
>>
>>
>> On Fri, Jun 28, 2013 at 8:49 AM, Stephen Loo <hingk...@gmail.com> wrote:
>>
>>> I have considered this, in quantum module, the continued_fraction
>>> function is only work for rational number a/b = continued_fraction(a, b),
>>> but my function above is work for float and depending on the precision. I
>>> don't know how to combine into single function, and it is not suggested to
>>> place in quantum module, it should be in ntheory.
>>>
>>> Stephen
>>>
>>> Thilina Rathnayake於 2013年6月28日星期五UTC+8上午10時58分36秒寫道：
>>>>
>>>>
>>>> Thanks guys for the help. Shouldn't we add this functionality to the
>>>> current continued_fraction or
>>>> add a new function to SymPy so user can use it directly?
>>>>
>>>>
>>>>
>>>> On Fri, Jun 28, 2013 at 7:45 AM, Stephen Loo <hing...@gmail.com> wrote:
>>>>
>>>>> def continued_fraction(r):
>>>>> while True:
>>>>> i = int(r)
>>>>> yield i
>>>>> if i == r:
>>>>> break
>>>>> r = 1 / (r - i)
>>>>>
>>>>>
>>>>> Thilina Rathnayake於 2013年6月28日星期五UTC+**8上午4時16分34秒寫道：
>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> Is there a function in sympy which gives the continued fraction
>>>>>> representation
>>>>>> of quadratic irrationalities like, (sqrt(17) + 5 ) / 4?
>>>>>>
>>>>>> I found an implementation of a continued fraction function in Shor's
>>>>>> algorithm:
>>>>>> http://docs.sympy.org/dev/**modu**les/physics/quantum/shor.**html<http://docs.sympy.org/dev/modules/physics/quantum/shor.html>
>>>>>>
>>>>>> But it doesn't seem to give correct results when irrationalities are
>>>>>> involved.
>>>>>>
>>>>>> >>> from sympy.physics.quantum.shor import continued_fraction
>>>>>>> >>> continued_fraction(sqrt(17)+5, 4)
>>>>>>> [2, 4]
>>>>>>>
>>>>>>
>>>>>> Actual answer should be 2, [3, 1, 1] with the numbers inside []
>>>>>> repeating forever.
>>>>>> Any help would be appreciated.
>>>>>>
>>>>>> Regards,
>>>>>> Thilina.
>>>>>> .
>>>>>>
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>>
>
Thilina Rathnayake,
Undergraduate,
Dept. of Comp. Sci.
UoM.
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