The error you're encountering with pip install blis on Termux (Fairphone 4, LineageOS 23.2) is likely due to BLIS (BLAS-like Library Instantly Sourced) requiring a C compiler and Python development headers to build from source. Termux has limitations compared to a full Linux environment, but here’s how to resolve it:

Solution for Termux

1. Install Required Dependencies

Run these commands in Termux to install the necessary tools:

pkg update && pkg upgrade
pkg install python clang libllvm

• clang: Provides the C compiler.
• libllvm: Required for BLIS compilation.

2. Set Environment Variables

BLIS needs to know where to find the compiler. Run:

export CC=clang
export CXX=clang++

3. Install BLIS via pip

Now try installing BLIS again:

pip install blis --no-binary=blis

• --no-binary=blis forces pip to build from source (required in Termux).

Alternative: Use Prebuilt Wheels

If the above fails, try installing a prebuilt wheel for aarch64 (ARM64) architecture:

pip install blis --prefer-binary

If no wheel is available, you may need to use a different BLAS library (e.g., numpy with OpenBLAS).

Fallback: Use OpenBLAS

If BLIS refuses to compile, install numpy with OpenBLAS (a compatible alternative):

pkg install openblas
pip install numpy

This avoids BLIS entirely but still provides optimized linear algebra.

Debugging Tips

• Check the full error log for missing dependencies.
• Ensure you’re using Python 3.8+ (python --version).
• If you see error: command 'clang' failed, verify clang is installed (which clang).

Question: Did you see a specific error message when running pip install blis? If so, share it here for a more targeted fix.