> I'm surprised it's expensive now.
Yeah amazon pricing is weird. My intent is for the book to be sold ~$30, but if I tell this price to amazon they start selling it for $20 after discounting, and then readers buy it less because they think it is not a complete book, but just some sort of summary notes. Nowadays I set the price to $40 so that after amazon discount the price will end up around $30, but today it is expensive indeed... I might have to bump it down to $35 at some point.
BTW, I've released several "point" updates and the book is now at v5.3. Please reach out by email if you're interested in having the PDF (I have a free-PDF-with-proof-of-purchase-of-print-version policy, including all updates).
Also some parts of the best parts of the book are available in full as standalone free tutorials:
SymPy = https://minireference.com/static/tutorials/sympy_tutorial.pd... ;
mechanics tutorial = https://minireference.com/static/tutorials/mech_in_7_pages.p... ;
concept maps = https://minireference.com/static/tutorials/conceptmap.pdf