FTTN (Feature-Targeted Testing for Numerical Properties of NVIDIA & AMD Matrix Accelerators) is a test suite to evaluate the numerical behaviors of GPU matrix accelerators (NVIDIA Tensor Cores and AMD Matrix Cores) in a quick and simple setting. Matrix accelerators are heavily used in today’s computationally intense applications to speed up matrix multiplications. This test suite provides a comprehensive study on the numerical behaviors of these accelerators, including support for subnormals, rounding modes, extra precision bits and FMA features.