Method get_density

tools/Assembler/Materials/Material.h:41–43

            throw NotImplementedError("strain_to_stress() is not implemented by subclasses.");
        }
        virtual Float get_density(VectorF coord) const {
            throw NotImplementedError("get_density() is not implemented by subclasses.");
        }
        virtual Float get_density() const {
            throw NotImplementedError("get_density() is not implemented by subclasses.");
        }