How PDF and CDF work?

Hi,

I need to make a pdf and cdf. I saw the documentation but I didn't understand how exactly can I used it.

I have power values. How can I make the cdf and pdf plot's with this values?

I am using that vector with the Power's values but in the plot appears a range absolutily nonsense. The power values are values between -140 and 10, and the values in the plot are like 0.1 ...

% --- Executes on button press in densityButton.
function densityButton_Callback(hObject, eventdata, handles)
% hObject    handle to densityButton (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
clear handles.Antena handles.nAntena handles.Movel 
i = handles.map.img(:,:,1)==255 & handles.map.img(:,:,2)==255 & ...
               handles.map.img(:,:,3)==255; 
Prx = handles.maxPrxArray;
minPower = round(handles.minPrx);
maxPower = round(handles.maxPrx);

eixoXX = minPower:maxPower;
size = length(Prx);

figure
plot(eixoXX,pdf('Normal',eixoXX))
grid on;

figure
plot(eixoXX, cdf('Normal', eixoXX))
grid on;

What I am doing wrong?

Thanks