A vector is defined as having three dimensions as being represented by an ordered collection of three numbers:   (X, Y, Z).

If you imagine a graph with the   x   and   y   axis being at right angles to each other and having a third,   z   axis coming out of the page, then a triplet of numbers,   (X, Y, Z)   would represent a point in the region,   and a vector from the origin to the point.

Given the vectors:

        A = (a1,  a2,  a3) 
        B = (b1,  b2,  b3) 
        C = (c1,  c2,  c3) 

then the following common vector products are defined:

 The dot product       (a scalar quantity)
  A • B = a1b1   +   a2b2   +   a3b3  
 The cross product       (a vector quantity)
  A x B = (a2b3  -   a3b2,     a3b1   -   a1b3,     a1b2   -   a2b1)  
 The scalar triple product       (a scalar quantity)
  A • (B x C) 
 The vector triple product       (a vector quantity)
  A x (B x C) 


Task

Given the three vectors:

        a = ( 3,    4,    5)
        b = ( 4,    3,    5)
        c = (-5,  -12,  -13)

 Create a named function/subroutine/method to compute the dot product of two vectors.
 Create a function to compute the cross product of two vectors.
 Optionally create a function to compute the scalar triple product of three vectors.
 Optionally create a function to compute the vector triple product of three vectors.
 Compute and display: a • b
 Compute and display: a x b
 Compute and display: a • (b x c), the scalar triple product.
 Compute and display: a x (b x c), the vector triple product.


References

   A starting page on Wolfram MathWorld is   Vector Multiplication .
   Wikipedia   dot product. 
   Wikipedia   cross product. 
   Wikipedia   triple product.


Related tasks

   Dot product
   Quaternion type


class MyVector(x, y, z) {
    method ∙(vec) {
        [self{:x,:y,:z}] »*« [vec{:x,:y,:z}] «+»
    }
 
    method ⨉(vec) {
        MyVector(self.y*vec.z - self.z*vec.y,
               self.z*vec.x - self.x*vec.z,
               self.x*vec.y - self.y*vec.x)
    }
 
    method to_s {
        "(#{x}, #{y}, #{z})"
    }
}
 
var a = MyVector(3, 4, 5)
var b = MyVector(4, 3, 5)
var c = MyVector(-5, -12, -13)
 
say "a=#{a}; b=#{b}; c=#{c};"
say "a ∙ b = #{a ∙ b}"
say "a ⨉ b = #{a ⨉ b}"
say "a ∙ (b ⨉ c) = #{a ∙ (b ⨉ c)}"
say "a ⨉ (b ⨉ c) = #{a ⨉ (b ⨉ c)}"