private SL2 Random()
{
var r = new SL2();
r[0][0] = GF127.Random();
r[0][1] = GF127.Random();
r[1][0] = GF127.Random();
// d = a^-1 * (1 + b*c)
r[1][1] = GF127.Inv(r[0][0]) * (r[0][1] * r[1][0] + new GF127(1, 0));
return(r);
}
public void TestInv()
{
foreach (var row in InvTestCases)
{
var c = GF127.Inv(row[0]);
Assert.AreEqual(row[1], c);
}
for (int i = 0; i < 4; i++)
{
var a = GF127.Random();
if (a.Equals(GF127.Zero))
{
continue;
}
var b = GF127.Inv(a);
var c = a * b;
Assert.AreEqual(new GF127(1, 0), c);
}
}