undeclared variable 'Enc_Char'

Unrecognized function or variable 'Enc_Char'.

Error in imp>pushbutton4_Callback (line 158)

[c(ii,1),c(iii,1)]=Enc_Char(c(ii,1),c(iii,1),F(i));

Error in gui_mainfcn (line 95)

feval(varargin{:});

Error in imp (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)imp('pushbutton4_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

[Walter Roberson]

already answered at https://www.mathworks.com/matlabcentral/answers/384332-getting-error-in-matlab-guide#comment_2281480