Because the PDF is text-searchable (most scans are), use the search bar aggressively. Type "Method of separation of variables" to jump directly to the rigorous derivation. This is the PDF’s superpower over the physical book.
Because the PDF is text-searchable (most scans are), use the search bar aggressively. Type "Method of separation of variables" to jump directly to the rigorous derivation. This is the PDF’s superpower over the physical book.