function x = dotProd( a, b )
% ===========================================
% Purpose: compute the dot product of two vectors
% Syntax:  x = dotProd( a, b ) 
% Inputs:  a = vector
%          b = vector
% Output:  x = a * b
% ===========================================

  m = length( a );
  k = length( b );
  if ( m~=k ),
    x = 'ERROR: vector dimensions do not agree';
    return, 
  end

  x = 0;
  for i=1:m,
      x = a( i ) * b( i ) + x;
  end