CAS Vars and integrals

[C.Ret]

Hello,

If you want the 't' variable to be local to your program, you have to declare it in the LOCAL statement. Otherwise, your code is using a global CAS variable named 't', that make it appears in the VAR CAS sub menu.

Try this :
#cas
Beta_r(z,a,b):=
BEGIN
LOCAL funz,t;
funz:=(t)→(t^(a-1)*(1-t)^(b-1));
RETURN int(funz(t),t,0,z);
END;
#end