Cheby can be tricky, textbook algorithms (eg, Saad's book) have some curve balls. Prometheus has a Cheby implementation that I know is correct. It was worked on by several good people and implemented in several codes and we wrote a paper on it. Mark On May 23, 2012, at 9:21 AM, Barry Smith wrote:

On May 22, 2012, at 4:17 PM, Hong Zhang wrote:

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Barry, Do you recall the paper or detailed Chebyshev algorithm that you implemented the Chebyshev in petsc?

No

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I added 'hybrid' to it, which is not correct. Jie is helping to fix it. Having an original algorithm would help.

The code has also heavily evolved since first being code with bells and whistles being added.

Perhaps look at the templates book for the definitive algorithm :-)

Barry

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On Tue, May 22, 2012 at 1:21 PM, Jie Chen <[email protected]> wrote: Then do you know who wrote the code? Hong said it was you.

It was written in the 90s, before version control history. Sorry, my mistake. I recall that Barry said that he wrote it when Jed was in dia... ;-( Hong

Hong is trying to modify the code but there is something wrong. I am helping to see what is the problem. The code itself is fine.

Hard to speculate without more than "something wrong".

Jie

----- Original Message ----- From: "Jed Brown" <[email protected]> To: "Jie Chen" <[email protected]>, "For users of the development version of PETSc" <[email protected]> Sent: Tuesday, May 22, 2012 1:18:07 PM Subject: Re: cheby.c

On Tue, May 22, 2012 at 12:37 PM, Jie Chen < [email protected] > wrote:

Jed, I am reading your implementation of the chebyshev code. The algorithm does not seem to be the same as the version I am familiar with. Did you implement it according to some paper or book?

I didn't write it.

What do you find strange?