The thing is, i did not write that i need an exact integer solution because
i don't like approximation, but because i am working in N^n and rounding
can cause catastrophically false results. The matrices i am working on are,
however, not all that big (i would guess absolute max 30x100, usually more
like 5x20).
Am Freitag, 15. Juli 2016 21:11:07 UTC+2 schrieb Chris Rackauckas:
>
> You're not going to get good runtimes with this if you're using Rationals.
> Each time a command is done, it needs to reduce the fraction. If you're
> working with small examples like you show here, then yes this can be
> worthwhile. However, even with good programming I don't think would scale
> to something like 1000x1000 systems.
>
> That said, this OverflowError() is may be because you're overflowing the
> integers? Try switching to Rational{BigInt} and see if you still get this
> error. This will decrease the performance even more though.
>
> I know that being Mathematician the prospect of getting an exact answer
> sounds nice, but there's a reason why it's not done very often. It's can
> become orders of magnitude more computationally intensive than even precise
> approximations. If you need something which is really precise, try
> BigFloats or Decimals.jl.
>
> On Friday, July 15, 2016 at 11:50:01 AM UTC-7, Kurolong wrote:
>>
>> Hey Guys and Gals ^^
>> I'm having trouble with Julia. Maybe one of you can help me out
>> The program i am writing requires the
>> linear-equation-system-solver(command "\") in the folder
>> "Julia-0.4.5\share\julia\base\linalg".
>> Now my problem is that i need the equation solved strictly on integers,
>> an approximate solution is of no use to me, which is why i tried working
>> with the "Rational" Type.
>> Curiously, the solver seems to work for the Rational Type if and only if
>> no pivoting is required. Otherwise, the following Error is thrown:
>>
>> WARNING: pivoting only implemented for Float32, Float64, Complex64 and
>> Complex128
>> ERROR: LoadError: OverflowError()
>> in * at rational.jl:188
>> [inlined code] from linalg/generic.jl:471
>> in reflector! at no file:0
>> in A_ldiv_B! at linalg/qr.jl:346
>> in \ at linalg/qr.jl:398
>> in \ at linalg/dense.jl:450
>> in include at boot.jl:261
>> in include_from_node1 at loading.jl:320
>> while loading C:\users\<username
>> omitted>\documents\julia-0.4.5\sg_project\v0.3\Test02.jl, in expression
>> starting on line 3
>>
>> Code to reproduce the Error:
>>
>> A=[[2//1,0//1] [3//1,3//2] [1//1,3//2]]
>> v=[2//1,0//1]
>> A\v
>>
>> Now i am under the impression that i could build a relatively simple
>> workaround if i knew exactly where in the developer's code the actual
>> problem is, but i am confused by the whole organization of the thing.
>> Building my own solver could certainly be done, but this will most likely
>> be ineffecient. Unfortunately, runtime is very important here, as the
>> method i am currently devising is supposed to be embedded in some very
>> expensive loops.
>>
>> I am a very unexperienced programmer and will likely not understand much
>> programmertalk, but i am a mathematician and will probably have little
>> problems in this respect.
>>
>> Maybe you have some ideas how to handle this problem.
>>
>> Thank you in advance for taking the time to look at my problem :)
>>
>
