MATLAB: Error Undefined function or variable

errorfunctionMATLABvariable

 
function [p,yy1]=graph999()
  f1=gcf(); 
  x0=str2num(char(inputdlg('Enter x0','Enter parametr',2,{'0'},'on')));
  if (x0<-2)|(x0>6) 
     msgbox('x0 should be between -2 and 6','Results') 
  else
  y0=str2num(char(inputdlg('Enter y0','Enter parametr',2,{'0'},'on')));
    if (y0<-5)|(y0>6)
        msgbox('y0 should be between -2 and 6','Results') 
    else
  k=str2num(char(inputdlg('Enter k','Enter parametr',2,{'0'},'on')));
  p=cos(y)+x.*y;
  yy1=ygr(x0,y0,k);
    end
  end
  
    
  function  yy=ygr(X,Y,k)
    x=-2:0.5:6;
    y=-5:0.5:6;
    [X,Y]=ndgrid(x,y);
    Z=(X^2).*sin(Y)+k;
    surf(X,Y,Z); 
    yy=Z;
It doesn't work with error
Undefined function or variable 'y'.
Error in graph999 (line 15)
p=cos(y)+x.*y;
What should I do for correct working?

Best Answer

function graph999  %main function
f1=gcf(); 
  x0=str2double(char(inputdlg('Enter x0','Enter parametr',2,{'0'},'on')));
  if (x0<-2)|(x0>6) 
     msgbox('x0 should be between -2 and 6','Results') 
  else
  y0=str2double(char(inputdlg('Enter y0','Enter parametr',2,{'0'},'on')));
    if (y0<-5)|(y0>6)
        msgbox('y0 should be between -2 and 6','Results') 
    else
  k=str2double(char(inputdlg('Enter k','Enter parametr',2,{'0'},'on')));
  [x,y]=ygr(k); %sub function call inside main function
    end
  end
    
    function  [x,y]=ygr(k)  %subfunction definition
    x=-2:0.5:6;
    y=-5:0.5:6;
    [X,Y]=ndgrid(x,y);
    Z=(X.^2).*sin(Y)+k;
    surf(X,Y,Z); 
    yy=Z;
  end
end
example of surface created:
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