From db93c5483757f3383e5a39641546dce6e0fa7dc1 Mon Sep 17 00:00:00 2001
From: Phillip Weinberg <weinbe58@gmail.com>
Date: Sat, 23 Dec 2023 09:21:02 -0500
Subject: [PATCH] fix bug.

---
 src/hinit.jl  | 12 ++++++------
 test/debug.jl |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/hinit.jl b/src/hinit.jl
index 638eb32..0bf0ba7 100644
--- a/src/hinit.jl
+++ b/src/hinit.jl
@@ -4,19 +4,19 @@ function euler_first_guess(solver::AbstractDPSolver{T}, hmax::T, posneg::T) wher
 
     dnf, dny = mapreduce(.+, solver.consts.atol_iter, solver.consts.rtol_iter, solver.k1, solver.y) do atoli, rtoli, f0i, yi
         sk = atoli + rtoli*abs(yi)
-        abs(f0i/sk)^2, abs(yi/sk)^2 # dnf, dny
+        (abs(f0i)/sk)^2, (abs(yi)/sk)^2 # dnf, dny
     end
 
+    println("euler_first_guess: dnf = $dnf, dny = $dny")
 
     if (dnf <= 1.0e-10) || (dny <= 1.0e-10)
         h = 1.0e-6
     else
         h = 0.01*sqrt(dny/dnf)
     end
-    h = min(h, hmax)
-    h = h * Base.sign(posneg)
 
-    return h, dnf
+    return min(h, hmax) * Base.sign(posneg), dnf
+
 end
 
 
@@ -48,14 +48,14 @@ function hinit(
     the increment for explicit euler is small
     compared to the solution
     =#
+    println("hinit: y = $(solver.y), k1 = $(solver.k1), k2 = $(solver.k2), k3 = $(solver.k3)")
     h, dnf = euler_first_guess(solver, hmax, posneg)
 
     ###### Perform an explicit step
     #y1 = y + h*f0
     #fcn(n, x+h, y1, f1)
-    # copyto!(solver.y1, solver.y + h*solver.k1)
     solver.y1 .= solver.y .+ h .*solver.k1
-    solver.f(solver.vars.x + h, solver.k3, solver.k2)
+    solver.f(solver.vars.x + h, solver.y1, solver.k2)
 
     ###### Estimate the second derivative of the solution
     der2 = estimate_second_derivative(solver, h)
diff --git a/test/debug.jl b/test/debug.jl
index c0dab55..cab8887 100644
--- a/test/debug.jl
+++ b/test/debug.jl
@@ -38,7 +38,7 @@ function run()
     println(report.num_rejected_steps)
     println(norm(solver.y))
     solver.vars.h
-    solver.y
+    @assert solver.y ≈ solution(1.0)
 
 end