function uplowH(fun,a,b,n,hObject)

handles=guidata(hObject);
t=[a:0.01:b];
f=fun(t);

axes(handles.upper);hold off;plot(t,f,'LineWidth',2);hold on; axis tight; title('Sumy górne');
axes(handles.lower);hold off;plot(t,f,'LineWidth',2);hold on; axis tight; title('Sumy dolne');


d=(b-a)/n;
valLOW=0;
valUP=0;
P=[a:d:b];
Q=fun(P);
size(P);

axes(handles.upper);
for i=1:n
    x=[P(i),P(i+1),P(i+1),P(i)];
    temp=fun([P(i):0.01:P(i+1)]);
    maxV=max(temp);
    y=[0,0,maxV,maxV];

    fill(x,y,'r','FaceAlpha', 0.4);
    valUP=valUP+d*maxV;
end
    set(handles.UPval,'String',num2str(valUP,'%.4f'))

    axes(handles.lower);
for i=1:n
    %pause(0.001);
    x=[P(i),P(i+1),P(i+1),P(i)];
    temp=fun([P(i):0.01:P(i+1)]);
    minV=min(temp);
    y=[0,0,minV,minV];

    fill(x,y,'g','FaceAlpha', 0.4);
    valLOW=valLOW+d*minV;

end
    set(handles.LOWval,'String',num2str(valLOW,'%.4f'))




axes(handles.lower); hold off
axes(handles.upper); hold off
end