In the line search we need to set the width of the search interval. After a discretization, the golden section search method is applied to the interval [p - searchDelta, p + searchDelta], where p is the point where the minimum value after the discretization was found.
The object searchDelta is a symbol.
The source of this document is in /build/reproducible-path/macaulay2-1.25.06+ds/M2/Macaulay2/packages/PHCpack/PHCpackDoc.m2:1804:0.