INTERFACE I4Extras;
(*
  Vector operations specific to 4-dimensional vector spaces.
  
  Created in Feb. 19, 1997 by Marcus Vinicius A. Andrade.
  Based in R4Extras.i3 by J. Stolfi.
*)

IMPORT MPInt, I4;

PROCEDURE Det(READONLY a, b, c, d: I4.T): MPInt.T;
  (*
    Returns the determinant of the matrix whose rows are "a", "b", "c". *)

PROCEDURE Cross(READONLY a, b, c: I4.T): I4.T;
  (*
    The cross product of "a", "b", "c" --- that is, a vector
    "r" orthogonal to all three, such that "Det(a, b, c, x) = Dot(r, x)"
    for any vector "x". *)

PROCEDURE GenerateOrtho(READONLY a: I4.T) : I4.T;
  (*
    Returns a 4-tuple orthogonal to "a", that is, returns "b" 
    such that "Dot(a,b) = 0"  *)
    
   
END I4Extras.