Fix direction bug in falsi

Author: kanav99

src/scalar.jl

@@ -128,7 +128,7 @@ function solve(prob::NonlinearProblem, ::Falsi, args...; maxiters = 1000, kwargs
       end
       mid = (fr * left - fl * right) / (fr - fl)
       for i in 1:10
-        mid = max(left, prevfloat_tdir(mid, prob.u0...))
+        mid = max_tdir(left, prevfloat_tdir(mid, prob.u0...), prob.u0...)
       end
       if mid == right || mid == left
         break

src/utils.jl

@@ -221,6 +221,10 @@ function nextfloat_tdir(x::T, x0::T, x1::T)::T where {T}
   x1 > x0 ? nextfloat(x) : prevfloat(x)
 end
 
+function max_tdir(a::T, b::T, x0::T1, x1::T1)::T where {T, T1}
+  x1 > x0 ? max(a, b) : min(a, b)
+end
+
 alg_autodiff(alg::AbstractNewtonAlgorithm{CS,AD}) where {CS,AD} = AD
 alg_autodiff(alg) = false