help: euler() prg on home mode

[compsystems]

Hello, the next numerical code, I want to run it in HOME MODE.

The definition v(t) does not allow me to define it within the code, Why?

PHP Code:

// file euler.hppprgm
export euler()
BEGIN
    local g,c,m,t;
    local vi,ti,vf,tf,iteration;
    //local v;
    purge(g,c,m,t,vi,ti,vf,tf);
    v(t):= vi+(g-(c/m)*vi)*(t-ti);
    g:=9.81; c:=12.5; m:=68.1;
    vi:=0;
    ti:=0;
    iteration:=1;
    print; // clear terminal view (output)
        print("euler");
    print("press [↓] for next iteration" );
    print("press [on] for exit" );
    wait(1);   
    FOR tf FROM 0 TO 10 STEP 2 DO
        print; // clear terminal view (output)
        print("iteration = "+iteration);
        vf:=v(tf);
        print("vi = "+vi+" m/s");
        print("ti = "+ti+" s");
        print("tf = "+tf+" s");
        print("vf("+tf+") = "+vf+" m/s");
        print("");
        vi:=vf;
        ti:=tf;
        iteration:=iteration+1; 
        wait();
    END;
    print("Iterations finished," );
    return("Done");
END; 


Source: NUMERICAL METHODS FOR ENGINEERS Steven C. Chapra & Raymond P. Canale



I managed to run it by doing the following trick.
Icomment the line // v(t):= vi+(g-(c/m)*vi)*(t-ti);
and I put in the line of entry (CAS MODE) the expression
v(t):= vi + (g- (c / m) * vi) * (t-ti);

euler() returns [] =(
but
[shift][1](program editor) euler
[DEBUG][CONT] [enter] ...[enter] ... ok
The program shows me screen by screen what I want
vi=0 m/s, ti=0 s , tf=0 s
v(0) = 0 m/s

vi=0, ti=0, tf=2
v(2) = 19.62 m/s

vi=19.62 m/s, ti=2 s, tf=4 s
v(4) = 32.04 m/s

vi=32.04 m/s, ti=4 s, tf=6 s
v(6") = 39.90 m/s
...

Please someone can help me by rewriting the above code to work well

Thanks

PS: In CAS mode if it works fine but how can I clean each screen? The print; command does not seem to be working. I have to clean each screen because the terminal view does not progress after the first impression screen is completed, (even hp-prime is a single process) should allow split screen and more of a process as did the hp48,

PHP Code:

// file euler1.hppprgm
// version simple MODO CAS
#cas
  euler1():=
  BEGIN
    local g,c,m,t;
    local vi,ti,vf,tf,iteration;
    local v;
    purge(g,c,m,t,vi,ti,vf,tf);
    v(t):= vi+(g-(c/m)*vi)*(t-ti);
    g:=9.81; c:=12.5; m:=68.1;
    vi:=0;
    ti:=0;
    iteration:=1;
    PRINT(); // clear terminal view (output)
    print("euler1");
    print("press [↓] for next iteration" );
    print("press [on] for exit" );
    wait(1);      
    FOR tf FROM 0 TO 10 STEP 2 DO
      PRINT(); // clear terminal view (output)
      print("iteration = "+iteration);
      vf:=v(tf);
      print("vi = "+vi+" m/s");
      print("ti = "+ti+" s");
      print("tf = "+tf+" s");
      print("vf("+tf+") = "+vf+" m/s");
      print("");
      vi:=vf;
      ti:=tf;
      iteration:=iteration+1; 
      wait();
    END;
    print("Iterations finished" );
    return("Done");
  END;
#end 


Debug mode does not work for CAS MODE = (, for this reason I want to create it in HOME MODE