"Source: Text/Geometry/GrpPSL2.text";
"Line: 495";
"Date: Tue Jun  7 22:27:14 2016";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Geometry/GrpPSL2.text, line: 495
// Example: H142E5 ()
print "Example: H142E5";
ei := GetEchoInput();
SetEchoInput(true);
G := CongruenceSubgroup(0,12);
Cusps(G);
Widths(G);
// Note that the sum of the cusp widths is the same as the Index:
&+Widths(G);
assert $1 eq 24;
Index(G);
assert $1 eq 24;
H := UpperHalfPlaneWithCusps();
[#EllipticPoints(Gamma0(N),H) : N in [1..20]];
// find the index where the maximal number of elliptic points is attained:
Max($1);
// find the elliptic points for Gamma0(13):
EllipticPoints(Gamma0(13));
SetEchoInput(ei);
