1. Mètodes especials

   1 from math import sqrt
   2 
   3 class Vector3d(object):
   4     """
   5     >>> from math import sqrt
   6     >>> v1 = Vector3d (1, 1, 1)
   7     >>> v2 = Vector3d (2, 3, 4)
   8     >>> v3 = Vector3d (5, 2, 1)
   9     >>> v1 + v2
  10     (3, 4, 5)
  11     >>> v1 - v2
  12     (1, 1, 1)
  13     >>> v2 * v3
  14     (10, 6, 4)
  15     >>> v1 * 2
  16     (2, 2, 2)
  17     >>> v1.modul() == sqrt(3)
  18     True
  19     """
  20     def __init__(self, x, y, z):
  21         self.x=x
  22         self.y=y
  23         self.z=z
  24 
  25     def __add__(self, v):
  26         self.x+=v.x
  27         self.y+=v.y
  28         self.z+=v.z
  29         return (self.x, self.y, self.z)
  30     
  31     def __sub__(self, v):
  32         self.x-=v.x
  33         self.y-=v.y
  34         self.z-=v.z
  35         return (self.x, self.y, self.z)
  36 
  37     def __mul__(self, v):
  38         if isinstance (v, Vector3d):
  39             self.x=self.x*v.x
  40             self.y=self.y*v.y
  41             self.z=self.z*v.z
  42         else:
  43             self.x=self.x*v
  44             self.y=self.y*v
  45             self.z=self.z*v
  46         return (self.x, self.y, self.z)        
  47 
  48     #falta el mètode producte vectorial associat a **
  49 
  50     def modul(self):
  51         mod = sqrt((self.x* self.x)+(self.y* self.y)+(self.z* self.z))
  52         return mod
  53 
  54     def cos_angle(self, v):
  55         return (self*v)/(self.modul()*v.modul())