September 2017 Update

Task/Vector-products/Stata/vector-products.stata

@@ -0,0 +1,43 @@
+mata
+real scalar sprod(real colvector u, real colvector v) {
+	return(u[1]*v[1] + u[2]*v[2] + u[3]*v[3])
+}
+
+real colvector vprod(real colvector u, real colvector v) {
+	return(u[2]*v[3]-u[3]*v[2]\u[3]*v[1]-u[1]*v[3]\u[1]*v[2]-u[2]*v[1])
+}
+
+real scalar striple(real colvector u, real colvector v, real colvector w) {
+	return(sprod(u, vprod(v, w)))
+}
+
+real colvector vtriple(real colvector u, real colvector v, real colvector w) {
+	return(vprod(u, vprod(v, w)))
+}
+
+a = 3\4\5
+b = 4\3\5
+c = -5\-12\-13
+
+sprod(a, b)
+  49
+
+vprod(a, b)
+        1
+    +------+
+  1 |   5  |
+  2 |   5  |
+  3 |  -7  |
+    +------+
+
+striple(a, b, c)
+  6
+
+vtriple(a, b, c)
+          1
+    +--------+
+  1 |  -267  |
+  2 |   204  |
+  3 |    -3  |
+    +--------+
+end