diff --git a/dependencies/reactor_class.js b/dependencies/reactor_class.js
index 0d73705..2c8d3b8 100644
--- a/dependencies/reactor_class.js
+++ b/dependencies/reactor_class.js
@@ -211,18 +211,15 @@ class Reactor_PFR {
                 const B = math.resize(math.diag(Array(this.n_x).fill(2/3), 1), [this.n_x, this.n_x]);
                 const C = math.resize(math.diag(Array(this.n_x).fill(-1/12), 2), [this.n_x, this.n_x]);
                 const D = math.add(I, A, B, C);
-                D[1][0] = -1;
-                D[1][1] = 0;
-                D[1][2] = 1;
-                D[1][3] = 0;
                 const NearBoundary = Array(this.n_x).fill(0.0);
-                NearBoundary[1] = -25/12;
-                NearBoundary[2] = 4;
-                NearBoundary[3] = -3;
-                NearBoundary[4] = 4/3;
-                NearBoundary[5] = -1/4;
+                NearBoundary[0] = -1/4;
+                NearBoundary[1] = -5/6;
+                NearBoundary[2] = 3/2;
+                NearBoundary[3] = -1/2;
+                NearBoundary[4] = 1/12;
+                D[1] = NearBoundary;
                 NearBoundary.reverse();
-                D[this.n_x-2] = NearBoundary;
+                D[this.n_x-2] = math.multiply(-1, NearBoundary);
                 D[0] = Array(this.n_x).fill(0); // set by BCs elsewhere
                 D[this.n_x-1] = Array(this.n_x).fill(0);
                 return D;