New Nonbinary Self-Dual Codes

In this correspondence, we construct new self-dual codes over F₄, F₅, F₇ with larger minimum weights than the previously known self-dual codes, using construction methods based on circulant and negacirculant matrices. In particular, a self-dual [36,18,13] code over F₇ is constructed which has a larger minimum weight than the previously known [36,18] codes.