the capacitor_value is returning Nan

% --- Executes on button press in calculate_button.

function calculate_button_Callback(hObject, eventdata, handles)

option = get(handles.resistance_value, 'value');

switch option

case 1

R = 1000;

case 2

R = 2000;

case 3

R = 3000;

case 4

R = 4000;

end

R = str2double(R);

f_c = get(handles.f_value,'string');

f_c = str2double(f_c);

c_value = 1 / (2*pi*R*f_c);

c_value = num2str(c_value);

set(handles.capacitor_value,'string',c_value);

Answer 1

[Voss]

In the switch block, R is set to a double already, so it is not correct to do str2double after that. In fact, doing so makes R into NaN:

% option = get(handles.resistance_value, 'value');
option = 1; % hard-coded for demonstration

switch option
    case 1
        R = 1000;
    case 2
        R = 2000;
    case 3
        R = 3000;
    case 4
        R = 4000;
end        
R = str2double(R)

R = NaN

So then C calculated from R=NaN is NaN as well:

% f_c = get(handles.f_value,'string');
f_c = '33'; % hard-coded for demonstration

f_c = str2double(f_c);
c_value = 1 / (2*pi*R*f_c)

c_value = NaN

c_value = num2str(c_value)

c_value = 'NaN'

Simply remove the erroneous R = str2double(R); line:

% option = get(handles.resistance_value, 'value');
option = 1; % hard-coded for demonstration

switch option
    case 1
        R = 1000;
    case 2
        R = 2000;
    case 3
        R = 3000;
    case 4
        R = 4000;
end        
% R = str2double(R);

% f_c = get(handles.f_value,'string');
f_c = '33'; % hard-coded for demonstration

f_c = str2double(f_c);
c_value = 1 / (2*pi*R*f_c)

c_value = 4.8229e-06

c_value = num2str(c_value)

c_value = '4.8229e-06'

[Badr Al-Sabri]

Thanks,

[Voss]

You're welcome! If that solves the problem, please click "Accept This Answer". Thanks!