diff --git a/EC_test.ipynb b/EC_test.ipynb
new file mode 100644
index 0000000..a6916ea
--- /dev/null
+++ b/EC_test.ipynb
@@ -0,0 +1,99 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "using Plots, LinearAlgebra\n",
+    "include(\"p_space.jl\")\n",
+    "\n",
+    "g0(R, p, q) = (exp(-(1/4)*(p + q)^2*R^2)*(-1 + exp(p*q*R^2))*R)/(2*sqrt(π))\n",
+    "g1(R, p, q) = (exp(-(1/4)*(p + q)^2*R^2)*(2 + p*q*R^2 + exp(p*q*R^2)*(-2 + p*q*R^2)))/(2*p*sqrt(π)*q*R)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "vertices = (0, 0.5 - 0.3im, 0.8, 6)\n",
+    "subdivisions = 64\n",
+    "p, w = get_mesh(vertices, subdivisions)\n",
+    "mesh_E = p.*p ./ (2*0.5)\n",
+    "\n",
+    "# ResonanceEC: Eq. (20)\n",
+    "V_system(c) = (p, q) -> c*(-5*g0(sqrt(3), p, q) + 2*g0(sqrt(10), p, q))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "training_points = range(0.75, 0.45, 5)\n",
+    "training_E = Vector{ComplexF64}(undef, length(training_points))\n",
+    "EC_basis = Matrix{ComplexF64}(undef, length(p), length(training_points))\n",
+    "\n",
+    "for (j, c) in enumerate(training_points)\n",
+    "    evals, evecs = eigen(get_H_matrix(V_system(c), p, w))\n",
+    "    i = identify_pole_i(p, evals)\n",
+    "    training_E[j] = evals[i]\n",
+    "    EC_basis[:, j] = evecs[:, i]\n",
+    "end\n",
+    "\n",
+    "scatter(real.(training_E), imag.(training_E), label=\"training\")\n",
+    "plot!(real.(mesh_E), imag.(mesh_E), label=\"contour\")\n",
+    "xlims!(0,1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "extrapolate_points = range(0.40, 0.20, 5)\n",
+    "extrapolate_E = Vector{ComplexF64}(undef, length(extrapolate_points))\n",
+    "exact_E = Vector{ComplexF64}(undef, length(extrapolate_points))\n",
+    "\n",
+    "for (j, c) in enumerate(extrapolate_points)\n",
+    "    H = get_H_matrix(V_system(c), p, w)\n",
+    "    evals = eigvals(H, permute=false)\n",
+    "    exact_E[j] = evals[identify_pole_i(p, evals)]\n",
+    "    \n",
+    "    EC_basis_w = EC_basis .* w\n",
+    "    H_EC = transpose(EC_basis) * H * EC_basis\n",
+    "    N_EC = transpose(EC_basis) * EC_basis\n",
+    "    evals = eigvals(H_EC, N_EC)\n",
+    "    i = argmin(abs.(evals .- exact_E[j]))\n",
+    "    extrapolate_E[j] = evals[i]\n",
+    "end\n",
+    "\n",
+    "scatter(real.(training_E), imag.(training_E), label=\"training\")\n",
+    "scatter!(real.(exact_E), imag.(exact_E), label=\"exact\")\n",
+    "scatter!(real.(extrapolate_E), imag.(extrapolate_E), label=\"extrapolated\")\n",
+    "plot!(real.(mesh_E), imag.(mesh_E), label=\"contour\")\n",
+    "xlims!(0,1)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Julia 1.9.0",
+   "language": "julia",
+   "name": "julia-1.9"
+  },
+  "language_info": {
+   "file_extension": ".jl",
+   "mimetype": "application/julia",
+   "name": "julia",
+   "version": "1.9.0"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}
diff --git a/p_space.jl b/p_space.jl
index a763c53..2883769 100644
--- a/p_space.jl
+++ b/p_space.jl
@@ -25,3 +25,18 @@ get_V_matrix(V_pq, p, w) = V_pq.(p, transpose(p)) .* transpose(w)
 get_K_matrix(p, μ) = collect(Diagonal(p.*p ./ (2*μ)))
 
 get_H_matrix(V_pq, p, w, μ=0.5) = get_K_matrix(p, μ) + get_V_matrix(V_pq, p, w)
+
+function identify_pole_i(p, evals, μ=0.5)
+    mesh_Es = (p.*p) ./ (2*μ)
+    
+    current_i = 0
+    current_min_ΔE = -1.0
+    for i in eachindex(evals)
+        min_ΔE = minimum(abs.(mesh_Es .- evals[i]))
+        if min_ΔE > current_min_ΔE
+            current_i = i
+            current_min_ΔE = min_ΔE
+        end
+    end
+    return current_i
+end
\ No newline at end of file