On Jan 24, 3:18 pm, Robert Kern <[EMAIL PROTECTED]> wrote:
> Ill-conditioned matrices. You should grab a copy of _Matrix Computations_ by
> Gene H. Golub and Charles F. Van Loan.
>
> For example, try the Hilbert matrix n=6.
>
> H_ij = 1 / (i + j - 1)
>
Sure enough, this gets ugly at n=6.
Thanks
Paul Rubin wrote:
> You might look at the Numerical Recipes books for clear descriptions
> of how to do this stuff in the real world. Maybe the experts here
> will jump on me for recommending those books since I think the serious
> numerics crowd scoffs at them (they were written by scientists ra
Paul McGuire wrote:
> On Jan 24, 1:47 pm, Robert Kern <[EMAIL PROTECTED]> wrote:
>> Paul McGuire wrote:
>>> And the purpose/motivation for "reimplementing it better" would be
>>> what, exactly? So I can charge double for it?
>> So you can have accurate results, and you get a good linear solver out
"Paul McGuire" <[EMAIL PROTECTED]> writes:
> Dang, I thought I was testing the results sufficiently! What is the
> accuracy problem? In my test cases, I've randomly created test
> matrices, inverted, then multiplied, then compared to the identity
> matrix, with the only failures being when I star
On Jan 24, 1:47 pm, Robert Kern <[EMAIL PROTECTED]> wrote:
> Paul McGuire wrote:
> > And the purpose/motivation for "reimplementing it better" would be
> > what, exactly? So I can charge double for it?
>
> So you can have accurate results, and you get a good linear solver out of the
> process. The
Paul McGuire wrote:
> And the purpose/motivation for "reimplementing it better" would be
> what, exactly? So I can charge double for it?
So you can have accurate results, and you get a good linear solver out of the
process. The method you use is bad in terms of accuracy as well as efficiency.
--
On Jan 24, 11:21 am, Gabriel Genellina <[EMAIL PROTECTED]> wrote:
> At Wednesday 24/1/2007 02:40, Paul McGuire wrote:
>
> > > The points should be aligned on a log-log plot to be a power function.
> > > As Robert Kern stated before, this problem should be not worse than
> > > O(n**3) - how have you
At Wednesday 24/1/2007 02:40, Paul McGuire wrote:
> The points should be aligned on a log-log plot to be a power function.
> As Robert Kern stated before, this problem should be not worse than
> O(n**3) - how have you implemented it?
>
Sure enough, the complete equation is t = 5e-05exp(1.1n), or
> The points should be aligned on a log-log plot to be a power function.
> As Robert Kern stated before, this problem should be not worse than
> O(n**3) - how have you implemented it?
>
Sure enough, the complete equation is t = 5e-05exp(1.1n), or t = 5e-05
X 3**n.
As for the implementation, it's p
At Tuesday 23/1/2007 22:33, Paul McGuire wrote:
On Jan 23, 6:59 pm, Robert Kern <[EMAIL PROTECTED]> wrote:
> Paul McGuire wrote:
> > I've posted a simple Matrix class on my website as a small-footprint
> > package for doing basic calculations on matrices up to about 10x10 in
> > size (no theoret
On Jan 23, 6:59 pm, Robert Kern <[EMAIL PROTECTED]> wrote:
> Paul McGuire wrote:
> > I've posted a simple Matrix class on my website as a small-footprint
> > package for doing basic calculations on matrices up to about 10x10 in
> > size (no theoretical limit, but performance on inverse is exponenti
Paul McGuire wrote:
> I've posted a simple Matrix class on my website as a small-footprint
> package for doing basic calculations on matrices up to about 10x10 in
> size (no theoretical limit, but performance on inverse is exponential).
Why is that? A simple and robust LU decomposition should be n
On Jan 23, 4:05 pm, Casey Hawthorne <[EMAIL PROTECTED]>
wrote:
> Do you calcalate the matrix inversion, when you don't need to?
>
No, the inversion is only calculated on the first call to inverse(),
and memoized so that subsequent calls return the cached value
immediately. Since the Matrix class
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