From 2f498367e8dfa7797a8a0192794fd38041cb0559 Mon Sep 17 00:00:00 2001
From: 2211567 <ruben.seitz@kiteit.de>
Date: Tue, 10 Jun 2025 12:07:13 +0200
Subject: [PATCH] adding a squiggle on the matrix now possible

---
 src/solver.jl | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/solver.jl b/src/solver.jl
index 3ddd9f0..16287aa 100644
--- a/src/solver.jl
+++ b/src/solver.jl
@@ -93,6 +93,33 @@ function circle_ic(N)
     return vec(u), vec(v)
 end
 
+function squiggle_ic(N, Lx=400.0, Ly=400.0)
+    uplus = 0.534522
+    vplus = 0.381802
+    uminus = -uplus
+
+    # Create coordinate grids
+    x = LinRange(0, Lx, N)
+    y = LinRange(0, Ly, N)
+    X = repeat(x', N, 1)  # Transposed to align with meshgrid X
+    Y = repeat(y, 1, N)   # Broadcasted to align with meshgrid Y
+
+    # Squiggle pattern
+    cos_term = 0.05 * Lx .* sin.(10 * 2π .* Y ./ Ly .+ π * 0.3)
+    exp_term = exp.(-((Y .- Ly / 2) ./ (0.1 * Ly)) .^ 2)
+    width = 0.05 * Lx
+    Z = exp.(-((X .- Lx / 2 .+ cos_term .* exp_term) ./ width) .^ 2)
+
+
+    u = fill(uplus, N, N)
+    v = fill(vplus, N, N)
+
+    # Apply squiggle
+    u[Z .> 0.8] .= uminus
+
+    return vec(u), vec(v)
+end
+
 
 """
     run_simulation(tspan::Tuple{Float64,Float64}, N::Int)
@@ -117,12 +144,12 @@ function run_simulation(tspan::Tuple{Float64,Float64}, N::Int)
     #v0 = vec(0.4 .+ 0.01 .* rand(N, N))
 
     # Or use this
-    u0, v0 = center_band_ic(N)
+    u0, v0 = squiggle_ic(N)
 
     y0 = vcat(vcat(u0, v0))
 
     prob = ODEProblem(fhn!, y0, tspan, p)
-    sol = solve(prob, BS3(), saveat=3.0)  # You can try `Rosenbrock23()` too
+    sol = solve(prob, BS3(), saveat=10.0)  # You can try `Rosenbrock23()` too
 
     return sol
 end