Método del trapecio en matlab.

Realizado en Matlab con  interfaz de usuario.

function calcular_Callback(hObject, eventdata, handles)
f=inline(get(handles.F,'string'));
a=str2num(get(handles.A,'string'));
b=str2num(get(handles.B,'string'));
n=str2double(get(handles.N,'string'));

    
h=(b-a)/n;
 s=f(a)+f(b);
  for i=2:n
      x(i)=a+(i-1)*h;
      s=s+2*f(x(i));
      
  end
  I=s*(h/2);
  set(handles.salida,'string',I);

% --- Executes on button press in graficar.
function graficar_Callback(hObject, eventdata, handles)
f=inline(get(handles.F,'string'));
a=str2num(get(handles.A,'string'));
b=str2num(get(handles.B,'string'));
n=str2double(get(handles.N,'string'));
h=(b-a)/n;
 for i=2:n
      x(i)=a+(i-1)*h;
      y(i)=f(x(i));
 end
  x=[x,b,a,a];
  y=[y,0,0,f(a)];
  fill(x,y,[0.8 0.8 0.9])
  for i=1:n+1;
      x(i)=a+(i-1)*h;
      y(i)=f(x(i));
  end
hold on
 ezplot(f,[min(x):0.2:max(x)]);
 plot(x,y,'og');
 plot(x,y,'g');
function salir_Callback(hObject, eventdata, handles)
close(gcbf);