Why I get Reference to a cleared variable x. in my code?

function data=surface_point(x,y)

clc, clear all, close all

   px = [0 50 100 150 200 250 300; 0 50 100 150 200 250 300; 0 50 100 150 200 250 300; 0 50 100 150 200 250 300];
   py = [0 0 0 0 0 0 0; 50 50 50 50 50 50 50;100 100 100 100 100 100 100;150 150 150 150 150 150 150];
   pz = [-15 70 90 -60 -40 15 40; 40 -5 -20 -40 50 30 -20; 0 -45 -30 30 40 -10 -40; -30 5 50 0 -30 -20 20];

n=size(px,1)-1;     
m=size(px,2)-1;
c=30;

u = x/300;
v = y/150;

          for i=1:n+1
              for j=1:m+1
                  sx=sx+px(i,j)*B(i-1,n,u)*B(j-1,m,v);
                  sy=sy+py(i,j)*B(i-1,n,u)*B(j-1,m,v);
                  sz=sz+pz(i,j)*B(i-1,n,u)*B(j-1,m,v);
              end
          end
  data = [sx sy sz];

[Stephen23]

"Why I get Reference to a cleared variable x. in my code?"

Because for no reason at all you put

clc, clear all, close all

at the start of your function. Why use some commands in your function if you don't know what they are doing? How are these commands in any way related to the functionality of what you are writing?

[NPNJ IT]

He probably wrote this without a function wrapper and forgot to remove that line before adding the function definition, having decided to wrap that code in a call.

Answer 1

[Image Analyst]

Because, although you pass in x and y, you delete them immediately with the command

clear all

Don't do that!!! If you don't do that, x will still be there when you need to use it.