Program: MKPERPVECT

  mkperpvect: construct perpendicular vector of line through 2 points
 
  call: n=mkperpvect(a,b);
 
        a: (number triple)
           a(1) is x coordinate of point A
           a(2) is y coordinate of point A
           a(3) is z coordinate of point A
        b: (number triple)
            coordinates of point B, analoguous to A
 
  result: n: vector that is perpendicular to the line defined by
             points A and B. (vector has unit length by constrution)
             n(1) is the x coordinate
             n(2) is the y coordinate
 
 
  The direction of the line through A and B is defined by the difference
  vector b-a.
  The direction of n is then defined by the condition that the dot product
  of n and b-a is zero when they are perpendicular. As additional
  condition, n is required to have unit length. (two equations are needed
  since a direction in a plane has to be defined)
 
  The resulting vector is in the plane defined by the vectors from
  coordinate origin to points A and B. In case you search the bisectors of
  a 3D triangle, this bisector is usually NOT in the plane of that
  triangle!
  If the 3D triangle is ABC and you want the perpendicular bisector for
  side AB, you  have t shift the coordinate origin into point C, what makes
  the sides AC and BC the vectors from coordinate origin to points A and B.
 
  Martin Knapmeyer, 02.12.2004

Read M-File Source Code


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