how to create a symbolic variable without using syms?

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Erwin Avendaño 2017-11-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/365434-how-to-create-a-symbolic-variable-without-using-syms

评论： Erwin Avendaño 2017-11-7

what happens is that I create a code that uses Symbolic Math Toolbox but they tell me that in the compiler it does not accept it then I want to declare a symbolic variable without using syms

my code

    function pushbutton3_Callback(~, ~, handles)
syms x %variable simbolica x
f=get(handles.edit8,'string');
xl=str2double(get(handles.edit3,'string'));
xu=str2double(get(handles.edit5,'string'));
tol=str2double(get(handles.edit4,'string'));
E=100;
xa=100;
i=0;
while(tol<E)
    xr=(xl+xu)/2;
    fxl=subs(f,x,xl);
    fxr=subs(f,x,xr);
    m=fxl*fxr;
    if(m)<0
          xu=xr;
      else
          xl=xr;
      end
      E=abs(xr-xa);
      xa=xr;
      i=i+1;
  end
  xr;
  vpa(E,5)
  set(handles.edit6,'string',xr);
  set(handles.edit9,'string',E);