+ return x * x;
+}
+
+static int check_point(parameters& p, double cr, double ci)
+{
+ double zr2, zi2;
+ zi2 = sqr(ci);
+ if (sqr(cr + 1) + zi2 < 1.0 / 16.0)
+ return p.maxiter;
+ double x4 = cr - 1.0 / 4.0;
+ double q = sqr(x4) + zi2;
+ if (q * (q + x4) < zi2 / 4.0)
+ return p.maxiter;
+ zr2 = sqr(cr);
+ double zr = cr;
+ double zi = ci;