[Solved] ld: library not found for -lntl

NTL: A Library for doing Number Theory

NTL is a high-performance, portable C++ library providing data structures and algorithms for manipulating signed, arbitrary length integers and for vectors, matrices, and polynomials over the integers and over finite fields.

You might face a linking error with NTL in macOS using the Apple Clang compiler:

% make                               

Consolidate compiler generated dependencies of target degrees

[ 25%] Linking CXX executable degrees

ld: library not found for -lntl

clang: error: linker command failed with exit code 1 (use -v to see invocation)

Solution:

% brew install NTL

% export LIBRARY_PATH=/usr/local/lib

% make

This linker error means the build was told to link NTL, the C++ number theory library, but cannot find it. NTL provides arbitrary length integers and operations on polynomials and matrices over rings and finite fields.

Installing NTL and pointing the linker at its library path resolves it. NTL also depends on GMP, so make sure that is installed and discoverable as well.