fix zero

src/integer.rs

@@ -453,7 +453,20 @@ impl Planar64{
 	}
 	#[inline]
 	pub fn sqrt(&self)->Self{
-		Planar64(unsafe{(((self.0 as i128)<<32) as f64).sqrt().to_int_unchecked()})
+		const BITS:i32=64;
+		const FRAC:i32=32;
+		let pow=(((BITS-FRAC-(self.0.leading_zeros() as i32)+1)>>1)+FRAC)-1;
+		let mut result=Self::ZERO;
+		let wide_self=(self.0 as i128)<<FRAC;
+		for i in (0..=pow).rev(){
+			let new_result=Self::raw(result.0|1<<i);
+			match wide_self.cmp(&((new_result.0 as i128)*(new_result.0 as i128))){
+				core::cmp::Ordering::Less=>(),
+				core::cmp::Ordering::Equal=>return new_result,
+				core::cmp::Ordering::Greater=>result=new_result,
+			}
+		}
+		result
 	}
 	#[inline]
 	pub const fn signum_i64(&self)->i64{