function =expandaxis(perleft, perright, perdown, perup)
%EXPANDAXIS Extends the current axis in any or all directions.
% EXPANDAXIS(left, right, down, up) Each of the direction will be expanded
% by the specified percent. For example if Left were specified as 30 then
% the upper bound of the axis would be increased by 30% of the vertical
% distance across the horizontal axis.
% If no argument is given, the routine will default to 10% in the
% unspecified directions.
% See also SHOWCIRC, SHOWRECT, SHOWVECT, SHOWX, SHOWY, TITLEBLOCK.
% Details are to be found in Mastering Mechanics I, Douglas W. Hull,
% Prentice Hall, 1998
% Douglas W. Hull, 1998
% Copyright (c) 1998-99 by Prentice Hall
% Version 1.00
axis([newleft newright newbottom newtop]);