I now have a working version of python3. Here's the steps in case anyone else has problems. Install Xcode (make sure to open and accept license) Install CLT from https://developer.apple.com/download/more/?=command%20line%20tools (otherwise software not found error with $ xcode-select --install) Install Homebrew brew install python (adds 3.9) add '/usr/local/opt/python@3.9/libexec/bin' to $PATH fix openblas with: $ export LDFLAGS="-L/usr/local/opt/openblas/lib"  and $ export CPPFLAGS="-I/usr/local/opt/openblas/include" 7. use pip3 to install packages I'm still interested in a non-Homebrew solution if such a thing is available. Never found one . . .

Thanks again, Etresoft, for your reply. Without Homebrew: If I install CLT from https://developer.apple.com/download/more/?=command%20line%20tools and then run  $pip3 install scipy I get an error saying "ERROR: Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/Library/Python/3.8'" The same for numpy. I'm using an admin account. If I can't install common python packages, I can't get a useable implementation of python3 on Catalina. This was not a problem for previous OS versions. Does anyone else have this problem?

Thank you, Etresoft, for your response. So you have successfully installed the scipy package for Python3 on Catalina? How did you do it? This isn't a Homebrew problem, but a Catalina problem. I was using Homebrew as the solution to install python3. If I install CLT from https://developer.apple.com/download/more/?=command%20line%20tools and then run $pip3 install scipy I get an error saying "ERROR: Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/Library/Python/3.8'" The same for numpy. I'm using an admin account. If I can't install common python packages, I can't get a useable implementation of python3 on Catalina. This was not a problem for previous OS versions. Does anyone else have this problem?