Mathmanman said:
@micromass I'm asking books for self study. Any other books or suggestions?
Here are some cheap books, I don't know PDE's myself so I'll just comment on what type of books they seem to be.
https://www.amazon.com/dp/0486438341/?tag=pfamazon01-20
This one looks pretty decent, it seems well organized and has the style I prefer which is to speak using the math. The other style is to try to explain first and use math later, but this can mean that one has more difficulty solving the problems.
It does have the character of needing one to think about what is being said, what does it mean, why is it relevant. I think the answers are there to be found but it needs some thought as one goes through it. But it seems like the author tries hard to be clear, so it shouldn't be a problem.
https://www.amazon.com/dp/0387906096/?tag=pfamazon01-20
This one reads more like a graduate book in the sense that not a lot is explained; claims are presented and one is expected to convince oneself that they are true. If you're the type of learner who likes to get it accurately and quickly, this would be good. But for each page you would need to look at each claim, decide why it is true, what is the import, write notes or summaries to allow you to reinforce that knowledge.
That said, the math used looks accessible so it won't be difficult from that point of view. So more initiative and diligence required but it looks good to me. For example, no reviewer had anything bad to say about it.
https://www.amazon.com/dp/0486652513/?tag=pfamazon01-20
This one looks more mathy in the sense of following a logical progression and using words like "suppose", "then" and "hence". One reviewer calls it intermediate level but is any PDE book going to be at the beginner level? If you prefer a proof book then this is a cheap option although consider that it seems to progress quite slowly.
https://www.amazon.com/dp/048668640X/?tag=pfamazon01-20
This older book seems to focus on methods of solving PDE's. Sometimes it is nice when first learning a subject to get a quick view of the practical side of things. It can help when learning theory to be able to say, oh yes, this is the theory of so-and-so which I have seen before. And this book is very cheap. So I think there is no beginner book but this is one way to try to fill in that beginning void.
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Just to say again, treat these as face-value reviews.