[iscConvex,g,sohs,h] = NCisCycConvex(f,precision) checks if the second directional derivative of a polynomial is cyclically equivalent to a sum of hermitian squares.

f is an NCpoly representing a polynomial.

With precision we can set the smallest value that is considered to be nonzero in numerical calculations; if the command is called without it, we assume the precision set with the command NCsetPrecision or the value set in NCparam.m.

iscConvex equals 1 if the second directional derivative of a polynomial f is cyclically equivalent to a sum of hermitian squares and 0 otherwise
g is an NCpoly representing the second derivative of the polynomial f
sohs is the SOHS decomposition of the polynomial cyclically equivalent to the second derivative of the polynomial f
h is the NCpoly representing sum_i m_i^*m_i cyclically equivalent to the second derivative of the polynomial f

NCisCycConvex(f), NCisCycConvex(f,precision)