HermiteDecomposition::latm
LatticeReduce::latm
The element 4.5 is a real number rather than an exact integer or a rational number:
LatticeReduce[{{1, 2}, {3, 4.5}}]The inexact number can be converted to an exact rational number using Rationalize:
LatticeReduce[Rationalize[{{1, 2}, {3, 4.5}}]]