# The Solver struct

HomotopyContinuation.SolverType
Solver(pathtracker::PathTracker)

A Solver is a wrapper around a given pathtracker to track multiple paths. It provides on top of the given pathtracker parallelization and an optional path jumping check. To construct a Solver it is convenient to use the solver or solver_startsolutions functions. Given a solver one can use the solve function to solve a system. This struct is constructed for any call to solve unless already explicitly provided.

Example

Assume we want to solve a polynomial system repeatedly for many different values of the parameters p. The following example shows how to use a Solver to avoid some computational overhead compared to naively calling solve.

@polyvar x y z p[1:3]
F = [
x + 3 + 2y + 2 * y^2 - p[1],
(x - 2 + 5y) * z + 4 - p[2] * z,
(x + 2 + 4y) * z + 5 - p[3] * z,
]
q = randn(ComplexF64, 3)
S = solutions(solve(subs(F, p => q)))
# create some fake parameter values
params = [randn(3) for _ = 1:1000]
# create a Solver to reuse for the path tracking
F_solver = solver(F; parameters = p, generic_parameters = q)
# solve the system F for all paramaters p in params
params_solutions = map(params) do p
solutions(solve(F_solver, S; target_parameters = p))
end