function [extraout] = rationaltransformplot(B,A,Wmax,extra1,extra2,extra3,extra4,extra5)

%written by Andrew Lambert to provide three-dee visualisation
%of a complex valued function in two variables. For example,
%the laplace or z-transform. Given the polynomial coefficients
%of the numerator, B, and the denominator, A, of the rational
%transfer function, it will plot a rotatable surface, of num by num points
%between x=y=-Wmax to x=y=Wmax. The plot shown will be
%either 'mag','phase','power','real','imag', and will have a
%'log' or 'linear' vertical axis.
% B and A being row vectors indiczte coefficients of polynomials
% B and A being column vectors indicates a list of poles and zeros respectively
% special options exist to show specific contours on the transform plane;
% These may be set be the strings 'ZRING','TOZRING',and 'SFREQAXIS' or by
% a MASK matrix showing which bits to show, e.g., chirp z-transform - TO BE DONE

% NOTE: We should also look for combinations of bad strings in the extralist
 if (nargin < 3) error('Not enough arguments'); return; end
  scale = 'linear';
  type = 2';
  num = 50;
  special = 0;
  masktomake = -1;
  alreadynum = 0;
  alreadyscale = 0;
  alreadytype = 0;
  
  B2 = poly(A); %assume input is poles and zeros (column vector)
  A2 = poly(B); %assume input is poles and zeros (column vector)
  [mA,nA]=size(A);
  [mB,nB]=size(B);
% now see if both are row vectors then we have numer(B) and denom(A) polys
  if ((mA==1)&(mB==1)) B2 = B; A2= A; end;
  [m,n]=size(B);
 
if (nargin > 3)
      if ~isstr(extra1) 
          num = extra1;
          alreadynum = 1;
      else
	      if strcmp(lower(extra1),'mag') type = 2; end;
	      if strcmp(lower(extra1),'phase') type = 3; end;
	      if strcmp(lower(extra1),'power') type = 4; end;
	      if strcmp(lower(extra1),'real') type = 0; end;
	      if strcmp(lower(extra1),'imag') type = 1; end;
	      if strcmp(lower(extra1),'log') scale = 'log'; end;
	      if strcmp(lower(extra1),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra1),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra1),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra1),'usemask') 
	              if (nargin > 4) mask=extra2; masktomake=0;
	              else error('A mask matrix must follow the USEMASK string'); end;
	              end
	      if strcmp(lower(extra1),'zringonly') masktomake = 1; end;
	      if strcmp(lower(extra1),'tozring') masktomake = 2; end;
	      if strcmp(lower(extra1),'sfreqonly') masktomake = 3; end;
      end
   end
   if (nargin > 4) & (~(masktomake == 0))
      if ~isstr(extra2) 
          if alreadynum error('Bad argument - too many numbers'); return; 
             else num = extra2; alreadynum = 1; end;
      else
	      if strcmp(lower(extra2),'mag') type = 2; end;
	      if strcmp(lower(extra2),'phase') type = 3; end;
	      if strcmp(lower(extra2),'power') type = 4; end;
	      if strcmp(lower(extra2),'real') type = 0; end;
	      if strcmp(lower(extra2),'imag') type = 1; end;
	      if strcmp(lower(extra2),'log') scale = 'log'; end;
	      if strcmp(lower(extra2),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra2),'usemask') 
	              if (nargin > 5) mask=extra3; masktomake = 0;
	              else error('A mask matrix must follow the USEMASK string'); end;
	              end
	      if strcmp(lower(extra2),'zringonly') masktomake = 1; end;
	      if strcmp(lower(extra2),'tozring') masktomake = 2; end;
	      if strcmp(lower(extra2),'sfreqonly') masktomake = 3; end;
      end
   end
   if (nargin > 5) & (~(masktomake == 0))
      if ~isstr(extra3) 
          if alreadynum error('Bad argument - too many numbers'); return;
             else num = extra3; alreadynum = 1; end;
      else
	      if strcmp(lower(extra3),'mag') type = 2; end;
	      if strcmp(lower(extra3),'phase') type = 3; end;
	      if strcmp(lower(extra3),'power') type = 4; end;
	      if strcmp(lower(extra3),'real') type = 0; end;
	      if strcmp(lower(extra3),'imag') type = 1; end;
	      if strcmp(lower(extra3),'log') scale = 'log'; end;
	      if strcmp(lower(extra3),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra3),'usemask') 
	              if (nargin > 6) mask=extra4; masktomake = 0;
	              else error('A mask matrix must follow the USEMASK string'); end;
	              end
	      if strcmp(lower(extra3),'zringonly') masktomake = 1; end;
	      if strcmp(lower(extra3),'tozring') masktomake = 2; end;
	      if strcmp(lower(extra3),'sfreqonly') masktomake = 3; end;
      end
   end
   if (nargin > 6) & (~(masktomake == 0))
      if ~isstr(extra4) 
          if alreadynum error('Bad argument - too many numbers'); return;
             else num = extra4; alreadynum = 1; end;
      else
	      if strcmp(lower(extra4),'mag') type = 2; end;
	      if strcmp(lower(extra4),'phase') type = 3; end;
	      if strcmp(lower(extra4),'power') type = 4; end;
	      if strcmp(lower(extra4),'real') type = 0; end;
	      if strcmp(lower(extra4),'imag') type = 1; end;
	      if strcmp(lower(extra4),'log') scale = 'log'; end;
	      if strcmp(lower(extra4),'linear') scale = 'linear'; end;
	      if strcmp(lower(extra4),'usemask') 
	              if (nargin > 7) mask=extra5; masktomake=0;
	              else error('A mask matrix must follow the USEMASK string'); end;
	              end
	      if strcmp(lower(extra4),'zringonly') masktomake = 1; end;
	      if strcmp(lower(extra4),'tozring') masktomake = 2; end;
	      if strcmp(lower(extra4),'sfreqonly') masktomake = 3; end;
      end
   end

if (masktomake==-1) mask = ones(num,num);
elseif masktomake==1
         mask = zeros(num,num);
         % fill mask out with ones if on zring 
         mask(:,:) = realmin;
         radius = (num/(2*Wmax));
         radiussqrmax = (radius + 0.49)^2;
         radiussqrmin = (radius - 0.49)^2;
         for p = 1:num
           for q = 1:num
              temp5 = (p-num/2)^2 + (q-num/2)^2;
              if ((temp5 < radiussqrmax) & (temp5 > radiussqrmin)) mask(p,q)=1; end;  
           end
         end
elseif masktomake==2 
         mask = zeros(num,num);
         mask(:,:) = realmin;
         %fill mask out with ones out to the zring
         radiussqr = (num/(2*Wmax)+0.49)^2;
         for p = 1:num
           for q = 1:num
              temp5 = (p-num/2)^2 + (q-num/2)^2;
              if (temp5 < radiussqr) mask(p,q)=1; end;  
           end
         end
         
elseif masktomake==3 
         mask = zeros(num,num);
         mask(:,:) = 0.00001; %realmin;
         %fill mask out with ones down the imaginary axis
         mask(:,num/2)=1;
end;

%myimagedisplay(mask);
        
myimage = zeros(num,num);

for p = 1:num
  rows(p,:)=linspace(-Wmax,Wmax,num);
  cols(:,p)=linspace(-Wmax,Wmax,num)';
  end
temp = rows+j*cols;

if type == 0 myimage=real(polyval(B2,temp)./polyval(A2,temp));
elseif type == 1 myimage=imag(polyval(B2,temp)./polyval(A2,temp));
elseif type == 2 myimage=abs(polyval(B2,temp)./polyval(A2,temp));
elseif type == 3 myimage=angle(polyval(B2,temp)./polyval(A2,temp));
elseif type == 4 myimage=(abs((polyval(B2,temp)./polyval(A2,temp)))).^2;
end;

myimage = myimage.*mask;

%if (myimage(:,:) > himax) myimage(:,:)=himax; end

%if (masktomake < 0) 
   surfl(rows,cols,myimage);
%else
%   meshz(rows,cols,myimage);
%end;

axis tight;
colormap hot; %pink

shading interp;

set(gca,'zscale',scale);
set(gca,'view',[30,45]);
ylabel('imag');
xlabel('real');
zlabel('|H|');
rotate3d;

if (nargout > 0) extraout=gca; end;

return;