MATLAB: How to make this code like a cycle

Question

clc
clear all
%Data
v1=1;  
x1=0; 
v2=1; 
E=10e-5; 
b1=-0.3; 
b2=-0.6; 
%Process
P=4*v2*sin(x1); % I Evaluate all this piece of code until
Q=-4*v2*cos(x1)+(4*(v2^2)); 
J=[4*v2*cos(x1) 4*sin(x1); 4*v2*sin(x1) 8*v2-4*cos(x1)]; 
A=[b2-P;b1-Q];
B=inv(J)*A;    
E1=B(1,:)
E2=B(2,:)
x1=x1+E1
v2=v2+E2 %this part  is evaluated in if (Note that x1 and v2 have a new value)
if abs(E1)>E || abs(E2)>E
    P=4*v2*sin(x1); 
    Q=-4*v2*cos(x1)+(4*(v2^2)); 
    J=[4*v2*cos(x1) 4*sin(x1); 4*v2*sin(x1) 8*v2-4*cos(x1)]; 
    
    A=[b2-P;b1-Q];
    B=inv(J)*A;    
    E1=B(1,:) %(Note that E1 and E2 have a new value)

    E2=B(2,:)
    x1=x1+E1
    v2=v2+E2 %(Note that x1 and v2 have a new value)

else 
    P=4*v2*sin(x1); 
    Q=-4*v2*cos(x1)+(4*(v2^2)); 
    J=[4*v2*cos(x1) 4*sin(x1); 4*v2*sin(x1) 8*v2-4*cos(x1)]; 
    
    A=[b2-P;b1-Q];
    B=inv(J)*A;    
    E1=B(1,:) %(Note that E1 and E2 have a new value)
    E2=B(2,:)
    x1=x1+E1
    v2=v2+E2 %(Note that x1 and v2 have a new value)
    
end 
% x1,v2,E1 and E2 are the values that change but x1 and v2 intials are given first, i wish to make a cycle for each new value of 
%variables mentioned, that is i want to make the process over and over again (evaluating the new values of the variables) until the 
% condition abs(E1)>E || abs(E2)>E is false, as you can see i can only value until a certain point (only two times) i want the code until the 
%conditon is false

Answer 1

JM - perhaps you can just replace the if/else block with

maxIterations = 1000;
atIteration = 0;
while (abs(E1)>E || abs(E2)>E) && atIteration <= maxIterations
    P=4*v2*sin(x1); 
    Q=-4*v2*cos(x1)+(4*(v2^2)); 
    J=[4*v2*cos(x1) 4*sin(x1); 4*v2*sin(x1) 8*v2-4*cos(x1)]; 
    
    A=[b2-P;b1-Q];
    B=inv(J)*A;    
    E1=B(1,:) %(Note that E1 and E2 have a new value)
    E2=B(2,:)
    x1=x1+E1
    v2=v2+E2 %(Note that x1 and v2 have a new value)
    
    atIteration = atIteration + 1;
end 

So the while loop would exit when both abs(E1) AND abs(E2) are less than E. (Or when the maximum number of iterations has been reached.)