The Octave control package uses the Uses SLICOT library, Copyright (c) 2020, SLICOT, available under the BSD 3-Clause (License and Disclaimer). SLICOT needs BLAS and LAPACK libraries which are also prerequisites for Octave itself. In case of failing tests, it is highly recommended to use Netlib’s reference BLAS and LAPACK for building Octave. Using ATLAS may lead to sign changes in some entries of the state-space matrices. In general, these sign changes are not ’wrong’ and can be regarded as the result of state transformations. Such state transformations (but not input/output transformations) have no influence on the input-output behaviour of the system. For better numerics, the control package uses such transformations by default when calculating the frequency responses and a few other things. However, arguments like the Hankel singular Values (HSV) must not change.

Source Code: test_control