ctr_surf.m

FISMAT accommodates different arithmetic operators, fuzzification and defuzzification algorithm, imp

function  [x,y,z] = ctr_surf(ctr,ts,bo,steps)

% [x,y,z] = ctr_surf(ctr,ts,bo,steps)
%
% Control surface of a two dimensional discrete fuzzy or neural controller.
%
% ctr = name of the controller (file). (Must be a string)
% ts  = sampling time - passed to the controller.
% bo  = [e-from e-to de-from de-to] = ranges for the x,y axes used for the
%       calculations.
%
% The controller must have to inputs. The warning 'divide by zero'
% can be caused by empty spaces in the rulebank and the division in the
% defuzzification routine.
%
% If this function is invoked without lefthand arguments, a surface and a
% contour plot is produced. 
% With lefthand arguments the plots can be displayed by 
% contour(x,y,z), surf(x,y,z) etc.
% 
% A big value for steps leads two more time needed for the calculation. 
% Start with step=10.
%
% FSTB - Fuzzy Systems Toolbox for MATLAB
% Copyright (c) 1993-1996 by Olaf Wolkenhauer
% Control Systems Centre at UMIST
% Manchester M60 1QD, UK
%
% 19-April-1994
 
bs=(bo(4)-bo(3))/steps;
as=(bo(2)-bo(1))/steps;
z=zeros(steps+1,steps+1); % +1 to get the full range.
disp('Working, please wait...')
e=bo(1);
xv=zeros(3,1);
% eset corresponds to the x-axis. deset corresponds to the y-axis.
for x=1:steps+1,          % x-axis corresponds to e - and the columns.
  de=bo(3);
  for y=1:steps+1,        % y-axis corresponds to de - and the rows.
    u=[e;de];
    o=feval(ctr,u,xv,ts); 
    z(y,x)=o;
    xv(1)=e; xv(3)=o;
    de=de+bs;
  end;
  xv(2)=de;
  e=e+as;
end;
x=linspace(bo(1),bo(2),steps+1);
y=linspace(bo(3),bo(4),steps+1);
if nargout==0,
  subplot(2,2,1),surf(x,y,z);
  subplot(2,2,2),contour(x,y,z);
end;