diff --git a/binary-tiling.cpp b/binary-tiling.cpp
index 147976d2..69aa5a44 100644
--- a/binary-tiling.cpp
+++ b/binary-tiling.cpp
@@ -148,8 +148,7 @@ namespace binary {
     }
   
   transmatrix parabolic(ld u) {
-    u = u * vid.binary_width / log(2);
-    return transmatrix {{{-u*u/8+1, u/2, u*u/8}, {-u/2, 1, u/2}, {-u*u/8, u/2, u*u/8+1}}};
+    return parabolic1(u * vid.binary_width / log(2) / 2);
     }
 
   void draw() {
diff --git a/hyperpoint.cpp b/hyperpoint.cpp
index 890fcecc..c1625082 100644
--- a/hyperpoint.cpp
+++ b/hyperpoint.cpp
@@ -319,6 +319,10 @@ transmatrix ypush(ld alpha) {
   return T;
   }
 
+transmatrix parabolic1(ld u) {
+  return transmatrix {{{-u*u/2+1, u, u*u/2}, {-u, 1, u}, {-u*u/2, u, u*u/2+1}}};
+  }
+
 // rotate the hyperbolic plane around C0 such that H[1] == 0 and H[0] >= 0
 transmatrix spintox(const hyperpoint& H) {
   transmatrix T = Id;