[SciPy-user] solve for symetric matrix ?
Nils Wagner
nwagner at iam.uni-stuttgart.de
Thu Apr 26 05:46:30 EDT 2007
fred wrote:
> Nils Wagner a écrit :
>
>> fred wrote:
>>
>>
>>> Nils Wagner a écrit :
>>>
>>>
>>>
>>>> Hi Fred,
>>>>
>>>> Yes.
>>>> See
>>>> http://en.wikipedia.org/wiki/Cholesky_decomposition#Computing_the_Cholesky_decomposition
>>>>
>>>>
>>>>
>>>>
>>> Thanks Nils !
>>>
>>>
>>>
>>>
>> Hi Fred,
>>
>> If you can't believe it run the attached script.
>>
>>
> Oh, I believe you, Nils ! ;-)
>
>> I get
>> python -i cholesky_lu.py
>> Elapsed time LU 0.291770935059
>> Residual 1.65732165386e-14
>> Elapsed time Cholesky 0.210819959641
>> Residual 1.8009241117e-14
>>
>>
> And me :-)
> Elapsed time LU 0.424935102463
> Residual 5.81146345637e-15
> Elapsed time Cholesky 0.253962039948
> Residual 5.74426431766e-15
>
> You titled 'LU' and used solve() method.
>
Yes solve() is for general matrices and based on an LU factorization.
> Do you mean that solve() use in fact LU decomposition ?
>
> PS : what cpu do you use (just for comparison ;-)
>
>
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 47
model name : AMD Athlon(tm) 64 Processor 3200+
stepping : 2
cpu MHz : 2000.138
cache size : 512 KB
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt
lm 3dnowext 3dnow pni lahf_lm
bogomips : 4009.73
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc
> Cheers,
>
>
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