Added source code

tests/maths.scad

@@ -0,0 +1,70 @@
+//
+// NopSCADlib Copyright Chris Palmer 2018
+// nop.head@gmail.com
+// hydraraptor.blogspot.com
+//
+// This file is part of NopSCADlib.
+//
+// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
+// GNU General Public License as published by the Free Software Foundation, either version 3 of
+// the License, or (at your option) any later version.
+//
+// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with NopSCADlib.
+// If not, see <https://www.gnu.org/licenses/>.
+//
+include <../core.scad>
+use <../utils/maths.scad>
+use <../utils/annotation.scad>
+
+tip = [0, 0, 20];
+
+module shape() {
+    cylinder(d1 = 20, d2 = 0, h = tip.z);
+}
+
+t = [10, 20, 30];
+r = [45, 20, 70];
+s = [1, 0.5, 0.75];
+
+module maths() {
+    //
+    // Translate, rotate and scale the shape
+    //
+    translate(t)
+        rotate(r)
+            scale(s)
+                shape();
+    //
+    // Apply the same transformations to the vector position of the tip
+    //
+    p = transform(tip, translate(t) * rotate(r) * scale(s));
+    //
+    // Place an arrow where the tip ends up
+    //
+    translate(p)
+        arrow();
+    //
+    // Unit vector pointing at p
+    //
+    u = unit(p);
+    //
+    // Point arrow in same direction
+    //
+    z = [0, 0, 1];
+    v = cross(u, z);
+    a = acos(u * z);
+
+
+    l = 20;
+    rotate(-a, v)
+        translate_z(l)
+            vflip()
+                arrow(l);
+}
+
+rotate(45)
+    maths();