Need assistance with Fourier analysis and GUI

function varargout = gui212(varargin)

% GUI212 MATLAB code for gui212.fig

%      GUI212, by itself, creates a new GUI212 or raises the existing

%      singleton*.
%
%      H = GUI212 returns the handle t0 a new GUI212 or the handle t0

%      the existing singleton*.

%
%      GUI212('CALLBACK',hObject,eventData,handles,...) calls the local

%      function named CALLBACK in GUI212.M with the given input arguments.
%

%      GUI212('Property','Value',...) creates a new GUI212 or raises the

%      existing singleton*.  Starting from the left, property value pairs are

%      applied t0 the GUI before gui212_OpeningFcn gets called.  An

%      unrecognized property name or invalid value makes property application

%      stop.  All inputs are passed t0 gui212_OpeningFcn via varargin.
%

%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one

%      instance t0 run (singleton)".

%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text t0 modify the response t0 help gui212

% Last Modified by GUIDE v2.5 13-Apr-2018 21:27:15

% Begin initialization code - DO NOT EDIT

gui_Singleton = 1;

gui_State = struct('gui_Name',       mfilename, ...

                     'gui_Singleton',  gui_Singleton, ...

                     'gui_OpeningFcn', @gui212_OpeningFcn, ...

                     'gui_OutputFcn',  @gui212_OutputFcn, ...

                     'gui_LayoutFcn',  [] , ...

                     'gui_Callback',   []);

if nargin && ischar(varargin{1})

      gui_State.gui_Callback = str2func(varargin{1});

end

if nargout

      [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});

else

      gui_mainfcn(gui_State, varargin{:});

end

% End initialization code - DO NOT EDIT

% --- Executes just before gui212 is made visible.

function gui212_OpeningFcn(hObject, eventdata, handles, varargin)

% This function has no output args, see OutputFcn.

% hObject    handle t0 figure

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% varargin   command line arguments t0 gui212 (see VARARGIN)

% Choose default command line output for gui212

handles.output = hObject;

% Update handles structure

guidata(hObject, handles);

% UIWAIT makes gui212 wait for user response (see UIRESUME)

% uiwait(handles.figure1);

% --- Outputs from this function are returned t0 the command line.

function varargout = gui212_OutputFcn(hObject, eventdata, handles) 

% varargout  cell array for returning output args (see VARARGOUT);

% hObject    handle t0 figure

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure

varargout{1} = handles.output;

function T0_Callback(hObject, eventdata, handles)

% hObject    handle t0 T0 (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of T0 as text

%        str2double(get(hObject,'String')) returns contents of T0 as a double

% --- Executes during object creation, after setting all properties.

function T0_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 T0 (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

function a0_Callback(hObject, eventdata, handles)

% hObject    handle t0 a0 (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of a0 as text

%        str2double(get(hObject,'String')) returns contents of a0 as a double

% --- Executes during object creation, after setting all properties.

function a0_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 a0 (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

function an_Callback(hObject, eventdata, handles)

% hObject    handle t0 an (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of an as text

%        str2double(get(hObject,'String')) returns contents of an as a double

% --- Executes during object creation, after setting all properties.

function an_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 an (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

function bn_Callback(hObject, eventdata, handles)

% hObject    handle t0 bn (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of bn as text

%        str2double(get(hObject,'String')) returns contents of bn as a double

% --- Executes during object creation, after setting all properties.

function bn_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 bn (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

function n_Callback(hObject, eventdata, handles)

% hObject    handle t0 n (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of n as text

%        str2double(get(hObject,'String')) returns contents of n as a double

% --- Executes during object creation, after setting all properties.

function n_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 n (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

function x_Callback(hObject, eventdata, handles)

% hObject    handle t0 x (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of x as text

%        str2double(get(hObject,'String')) returns contents of x as a double

% --- Executes during object creation, after setting all properties.

function x_CreateFcn(hObject, eventdata, handles)

% hObject    handle t0 x (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

%       See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

      set(hObject,'BackgroundColor','white');

end

% --- Executes on button press in Run.

function Run_Callback(hObject, eventdata, handles)

% hObject    handle t0 Run (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

axes(handles.axes1);

T0 = str2double(get(handles.T0, 'String'));

a0 = str2double(get(handles.a0, 'String'));

bn = str2double(get(handles.bn, 'String'));

an = str2double(get(handles.an, 'String'));

max_N = str2double(get(handles.n, 'String'));

xrange = str2double(get(handles.x, 'String'));

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

plot(x,f)

function [x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

x=xrange;

% frequency wn

w=2*pi/T0;

% initializing f at a0

f=a0;

syms n;

% Fourier series implementation

for n=1:max_N

      an2=eval(an);

      bn2=eval(bn);

      f=f+an2*cos(w*n*x)+bn2*sin(w*n*x);

end

These are my errors

Error using eval

Must be a string scalar or character vector.

Error in gui212>my_Fourier_series_generator (line 244)

      an2=eval(an);

Error in gui212>Run_Callback (line 226)

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

Error in gui_mainfcn (line 95)

          feval(varargin{:});

Error in gui212 (line 42)

      gui_mainfcn(gui_State, varargin{:});

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)gui212('Run_Callback',hObject,eventdata,guidata(hObject)) 

Error while evaluating UIControl Callback.

These are the arguments i entered

t0=2 a0=0.504 an=0.504*(2/(1+(16*(n^2)))) bn=0.504*((8*n)/(1+(16*(n^2)))) xrange=0:0.1:10 n=500

Answer 1

[Walter Roberson]

You have

an = str2double(get(handles.an, 'String'));

so we know that an must be a double (and would be NaN if the an edit field did not contain a valid scalar.)

You call

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

so you are passing that scalar (possibly nan) value as the third parameter to the function.

Inside the function you have

      an2=eval(an);

so you are trying to eval() that scalar double. It is not permitted to eval() a scalar double: you can only eval() a string object or a character vector.

[Christopher Carey]

So I removed str2doulbe but now my output is:

x =

   NaN

f =

   NaN

[Walter Roberson]

Did you remove the str2double() for bn as well?

[Christopher Carey]

yes i did

[Walter Roberson]

Revised code, please.

[Christopher Carey]

% --- Executes on button press in Run.

function Run_Callback(hObject, eventdata, handles)

% hObject    handle t0 Run (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

axes(handles.axes1);

T0 = str2double(get(handles.T0, 'String'));

a0 = str2double(get(handles.a0, 'String'));

bn = (get(handles.bn, 'String'));

an = (get(handles.an, 'String'));

max_N = str2double(get(handles.n, 'String'));

xrange = str2double(get(handles.x, 'String'));

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

plot(x,f)

function [x,f]=my_Fourier_series_generator(T0,a0,an,bn,xrange,max_N)

x=xrange;

% frequency wn

w=2*pi/T0;

% initializing f at a0

f=a0;

syms n;

% Fourier series implementation

for n=1:max_N

      an2=eval(an);

      bn2=eval(bn);

      f=f+an2*cos(w*n*x)+bn2*sin(w*n*x);

end

[Walter Roberson]

You indicate that you set xrange=0:0.1:10 so I assume this means that you typed in 0:0.1:10 into the edit box for handles.x . When you str2double() that, you are going to get NaN. str2double() can only accept scalar values.

You should be using separate boxes for lower bound, upper bound, and increment.

[Christopher Carey]

i see thank you very much this worked

[Christopher Carey]

however im getting an error when trying a different input these are the inputs

 T0=1 a0=1/2 bn=0 an=2/(n*pi)*sin(n*pi/2) bn=0 n=100 xmin=-10 xmax=10 xincrement=0.01

this is my code now

function Run_Callback(hObject, eventdata, handles)

% hObject    handle t0 Run (see GCBO)

% eventdata  reserved - t0 be defined in a future version of MATLAB

% handles    structure with handles and user data (see GUIDATA)

axes(handles.axes1);

T0 = str2double(get(handles.T0, 'String'));

a0 = str2double(get(handles.a0, 'String'));

bn = (get(handles.bn, 'String'));

an = (get(handles.an, 'String'));

max_N = str2double(get(handles.n, 'String'));

xmin = str2double(get(handles.x1, 'String'));

xmax = str2double(get(handles.x2, 'String'));

xincrement = str2double(get(handles.x3, 'String'));

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xmin,xmax,xincrement,max
_N)

plot(x,f)

function 
[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xmin,xmax,xincrement,max_N)

x1=xmin;

x2=xmax;

x3=xincrement;

x=xmin:xincrement:xmax;

% frequency wn

w=2*pi/T0;

% initializing f at a0

f=a0;

syms n;

% Fourier series implementation

for n=1:max_N

      an2=eval(an);

      bn2=eval(bn);

      f=f+an2*cos(w*n*x)+bn2*sin(w*n*x);

end

This is my error now

Error using gui212>my_Fourier_series_generator (line 248)

Error: This statement is incomplete.

Error in gui212>Run_Callback (line 228)

[x,f]=my_Fourier_series_generator(T0,a0,an,bn,xmin,xmax,xincrement,max_N)

Error in gui_mainfcn (line 95)

          feval(varargin{:});

Error in gui212 (line 42)

      gui_mainfcn(gui_State, varargin{:});

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)gui2

12('Run_Callback',hObject,eventdata,guidata(hObject)) 

Error while evaluating UIControl Callback.

[Walter Roberson]

We do not know which line is line 248

Reminder:

>> str2double('1/2')
ans =
   NaN

1/2 is not a scalar double, it is an expression and cannot be handled by str2double()