fzero_all

Extends functionality of fzero by dividing interval into sub-intervals and applying fzero on them.

Attempts to find zeros of f in a given by sampling f at N points inside the interval. The function then looks for intervals where f changes sign and applies fzero on them. If max_sols is specified, this function always returns vectors of length |max_sols| so the calling function may easily store the result in a matrix. WARNING: This function will not find roots of even multiplicity (x-x0)^2 and may miss other roots if they are spaced closer than the sampling interval.