bfit package on intel/M2 machine

[chengdang]

Update instruction of for building delta fit package https://github.com/JCSDA-internal/crtm/tree/feature/CD_bfit

Encountered multiple issues with f2py on both Intel and M2 machines, will document the solution here for future LUT generation.

[chengdang]

On intel machine, I encountered the following error:

ld: library not found for -lSystem
collect2: error: ld returned 1 exit status

Which is resolved by adding the following line in .zshrc:

export LIBRARY_PATH="$LIBRARY_PATH:/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib"

[chengdang]

On M1/M2 machine, I encountered the following error when importing bfit:

mach-o file, but is an incompatible architecture (have 'arm64', need 'x86_64')

Tried to install/reinstall various packages, but couldn't find a solution by far.

[chengdang]

Closing this issue for now.