Error Undefined function or variable

 
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?

Answer 1

[madhan ravi]

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:

[Mariya Shilovskaya]

You're the wizard! Thanks a lot!

[Stephen23]

It is recommended to use str2double rather than str2num (which hides an eval call inside).

[madhan ravi]

Anytime :) ,

Another easy way to produce surface:(requires symbolic toolbox)

syms x y
k=input('k value ? ')
ezsurf(x^2*sin(y)+k)