On 9/19/23 09:32, Lance Zhang wrote:
I would like to use this method to get the optimization of a original object
beam to get a shape of optimized object, for example , the shape of bridge.
Lance:
As I have mentioned on other occasions before, you need to learn to ask better
questions. I asked
> Right. But what's the operation you want to do with dJ/dΘ? Do you actually
> have to have it element by element, or do you want to do a product with
> this, etc?
but your reply does not actually address this. Instead, your reply was at a
level that is far too high and has nothing to do with the concrete problem of
dJ/dΘ any more. People have written whole books and PhD theses about shape
optimization; the topic is far larger than what can be answered on a mailing list.
There is an art to asking questions. If you ask too specific a question (say,
how do I store dJ/dΘ), then we can give you an answer that does that specific
thing but that does not lead to a practical algorithm because it does not
scale to large problems; but because you do not provide us with the context,
we can not know what it is you want to do that led you to this very specific
question. On the other hand, if questions are too general (say, "I want to do
shape optimization"), then all we can really do is to say "go to the library
and look up specific algorithms". There is a middle ground of questions of the
form "I am working on solving shape optimization problems and in the algorithm
I want to implement, there is a step where I need to multiply dJ/dΘ by a
vector x so that I can get the search direction; how does one efficiently
implement this kind of step? Do I need to store dJ/dΘ somehow, and if so how?"
Oftentimes, this sort of question involves writing half a page of text, but
you will get better answers if you provide context.
My suggestion would be that you work more closely with your adviser where you
can go back and forth between questions and answers more easily than is
possible on a mailing list. Perhaps your adviser can also help you find where
that middle ground of good questions is. That's the role of an adviser, and
that's a role we cannot fill on the mailing list.
Best
W.
--
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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