libimath-dev binary package in Ubuntu Lunar riscv64

 Imath is a basic, light-weight, and efficient C++ representation of
 2D and 3D vectors and matrices and other simple but useful
 mathematical objects, functions, and data types common in computer
 graphics applications, including the “half” 16-bit floating-point type.
 .
 Imath also includes optional Python bindings for all types and
 functions, including optimized implementations of vector and
 matrix arrays.
 .
 This package provides the development files for Imath.

Source package