Command: cos
  
Syntax: 
  x2 = cos(x1)
  
Description: 
  Return the cosine of x1, where x1 is in radians.
  
Comments: 
  This function may be applied to an atom or to all elements
  of a sequence.
  
Example: 
     x = cos({.5, .6, .7})
       
       -- x is {0.8775826, 0.8253356, 0.7648422}
 
See Also: 
  sin, tan, log, sqrt
  
