Function: mspadicinit
Section: modular_symbols
C-Name: mspadicinit
Prototype: GLLD-1,L,
Help: mspadicinit(M, p, n, {flag}): M being a full modular symbol space,
 as given by msinit and a prime p, initialize
 technical data needed to compute with overconvergent modular symbols
 (modulo p^n). If flag is unset or >= k-1, allow all symbols; else
 initialize only for symbols s such that Tp(s) = ap * s, with v(ap,p) <= flag.
Doc: $M$ being a full modular symbol space, as given by \kbd{msinit}, and $p$
 a prime, initialize technical data needed to compute with overconvergent
 modular symbols, modulo $p^n$. If $\fl$ is unset of $\fl \geq k-1$, allow
 all symbols; else initialize only for symbols $s$ such that $T_p(s) = a_p s$,
 with $v_p(a_p) \leq \fl$, which is faster. (The fastest initialization
 is obtained for $\fl = 0$ where we only allow ordinary symbols.)
 For supersingular eigensymbols, such that $p\mid a_p$, we must further
 assume that $p$ does not divide the level.

 \bprog
 ? E = ellinit("11a1");
 ? [M,xpm] = msfromell(E,1);
 ? ellap(E,3)
 %3 = -1
 ? Mp = mspadicinit(M, 3, 10, 0); \\ commit to ordinary symbols
 ? XPM = mstooms(Mp,xpm);
 @eprog
