undefind variableserror in the command window

I am new to matlab, and I am trying to write a simple function that changes between two numbers in a row of a matrix, but it doesn't work for some reason. This the function I wrote:

function [] = swibt( row1,num1,num2 )
  %UNTITLED3 Summary of this function goes here
  %   Detailed explanation goes here
  wibt1=x(row1,num1);
  x(row1,num1)=x(row1,num2);
  x(row1,num2)=wibt1;
end

when i type this in the command window it gives me an error alert and does not work:

>> instein(1)

x =

     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5

ans =

     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5
     1     2     3     4     5

>> swibt(1,1,2)
Undefined function or variable "x".

Error in swibt (line 4)
wibt1=x(row1,num1);

Can anyone help me, because I can't figure it out?

Answer 1

[Image Analyst]

You need to pass x into the function when you call it:

function test()
  x = rand(30,50);
  newX = swibt(1,2,3,x);

function x = swibt( row1,num1,num2, x )
  % Swap numbers
  wibt1=x(row1,num1);
  x(row1,num1)=x(row1,num2);
  x(row1,num2)=wibt1;
end

[Image Analyst]

Did that not work for you?

[asaf]

no it didnt work out but i think i understood the problem. another thing i heard is that i can use a matfile to store all the vriables so that all the function will be able to take information from it because the code i am writing has a lot of vriables how can it be done? thank you