function callcheck(htext,str1,z,vchk1,vchk2)
cla,set(htext,'string',[str1,sprintf('%1.4g\',z)]);	%	<2>
dt=0.1;t=0:dt:15;N=length(t);y=step(1,[1 2*z 1],t);plot(t,y);
if vchk1 									%						<4>
   [ym,km]=max(y);
   if km<(N-3)							%			<6>
      k1=km-3;k2=km+3;k12=k1:k2;tt=t(k12);
      yy=spline(t(k12),y(k12),tt);						%			<8>
      [yym,kkm]=max(yy);								%
      line(tt(kkm),yym,'marker','.',...				%				<10>
         'markeredgecolor','r','markersize',20);
      ystr=['ymax = ',sprintf('%1.4g\',yym)];
      tstr=['tmax = ',sprintf('%1.4g\',tt(kkm))];
      text(tt(kkm),1.05*yym,{ystr;tstr})
   else									%	<15>
      text(10,0.4*y(end),{'ymax --> 1';'tmax --> inf'})
   end
end
if vchk2						
   k95=min(find(y>0.95));k952=[(k95-1),k95];
   t95=interp1(y(k952),t(k952),0.95);	
   line(t95,0.95,'marker','o','markeredgecolor','k','markersize',6);
   tstr95=['t95 = ',sprintf('%1.4g\',t95)];
   text(t95,0.65,tstr95)
end