diff --git a/src/__comm__/__fast_fibonacci.scad b/src/__comm__/__fast_fibonacci.scad
index c082565d..aa1ddaee 100644
--- a/src/__comm__/__fast_fibonacci.scad
+++ b/src/__comm__/__fast_fibonacci.scad
@@ -1,15 +1,12 @@
-function __fast_fibonacci_sub(nth) = 
+function __fast_fibonacci_2_elems(nth) =
+    nth == 0 ? [0, 1] :
     let(
         _f = __fast_fibonacci_2_elems(floor(nth / 2)),
         a = _f[0],
         b = _f[1],
         c = a * (b * 2 - a),
-        d = a ^ 2 + b ^ 2
+        d = _f * _f
     ) 
     nth % 2 == 0 ? [c, d] : [d, c + d];
-
-function __fast_fibonacci_2_elems(nth) =
-    nth == 0 ? [0, 1] : __fast_fibonacci_sub(nth);
     
-function __fast_fibonacci(nth) =
-    __fast_fibonacci_2_elems(nth)[0];
\ No newline at end of file
+function __fast_fibonacci(nth) = __fast_fibonacci_2_elems(nth)[0];
\ No newline at end of file
diff --git a/src/__comm__/__half_trapezium.scad b/src/__comm__/__half_trapezium.scad
index 67c8d249..72b2f9ee 100644
--- a/src/__comm__/__half_trapezium.scad
+++ b/src/__comm__/__half_trapezium.scad
@@ -5,14 +5,14 @@ function __tr__corner_t_leng_lt_zero(frags, t_sector_angle, l1, l2, h, round_r)
     let(t_height = tan(t_sector_angle) * l1 - round_r / sin(90 - t_sector_angle) - h / 2)
     [ 
         for(pt = __pie_for_rounding(round_r, 90 - t_sector_angle, 90, frags * t_sector_angle / 180))
-            [pt[0], pt[1] + t_height]
+            [pt.x, pt.y + t_height]
     ];
 
 function __tr_corner_t_leng_gt_or_eq_zero(frags, t_sector_angle, t_leng, h, round_r) = 
     let(offset_y = h / 2 - round_r)
     [
         for(pt = __pie_for_rounding(round_r, 90 - t_sector_angle, 90, frags * t_sector_angle / 360))
-            [pt[0] + t_leng, pt[1] + offset_y]
+            [pt.x + t_leng, pt.y + offset_y]
     ];    
 
 function __tr_corner(frags, b_ang, l1, l2, h, round_r) = 
@@ -29,14 +29,14 @@ function __tr__corner_b_leng_lt_zero(frags, b_sector_angle, l1, l2, h, round_r)
     [
         for(i = [0:leng - 1])
             let(pt = reversed[leng - 1 - i])
-            [pt[0], -pt[1]]
+            [pt.x, -pt.y]
     ];
 
 function __br_corner_b_leng_gt_or_eq_zero(frags, b_sector_angle, l1, l2, b_leng, h, round_r) = 
     let(half_h = h / 2) 
     [
         for(pt = __pie_for_rounding(round_r, -90, -90 + b_sector_angle, frags * b_sector_angle / 360))
-            [pt[0] + b_leng, pt[1] + round_r - half_h]
+            [pt.x + b_leng, pt.y + round_r - half_h]
     ];
 
 function __br_corner(frags, b_ang, l1, l2, h, round_r) =