From ac7d9f5c3b04d938fb25a750497b3e9d32541734 Mon Sep 17 00:00:00 2001
From: Quaternions <krakow20@gmail.com>
Date: Thu, 29 Aug 2024 13:30:48 -0700
Subject: [PATCH] test more

---
 fixed_wide/src/fixed.rs |  2 ++
 fixed_wide/src/tests.rs | 26 ++++++++++++++++++--------
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/fixed_wide/src/fixed.rs b/fixed_wide/src/fixed.rs
index 4fa36fa..c39e31d 100644
--- a/fixed_wide/src/fixed.rs
+++ b/fixed_wide/src/fixed.rs
@@ -12,6 +12,8 @@ impl<const CHUNKS:usize,Frac:Unsigned> Fixed<CHUNKS,Frac>{
 	pub const MAX:Self=Self{bits:BInt::<CHUNKS>::MAX,frac:PhantomData};
 	pub const MIN:Self=Self{bits:BInt::<CHUNKS>::MIN,frac:PhantomData};
 	pub const ZERO:Self=Self{bits:BInt::<CHUNKS>::ZERO,frac:PhantomData};
+	pub const EPSILON:Self=Self{bits:BInt::<CHUNKS>::ONE,frac:PhantomData};
+	pub const NEG_EPSILON:Self=Self{bits:BInt::<CHUNKS>::NEG_ONE,frac:PhantomData};
 	pub const ONE:Self=Self{bits:BInt::<CHUNKS>::ONE.shl(Frac::U32),frac:PhantomData};
 	pub const TWO:Self=Self{bits:BInt::<CHUNKS>::TWO.shl(Frac::U32),frac:PhantomData};
 	pub const HALF:Self=Self{bits:BInt::<CHUNKS>::ONE.shl(Frac::U32-1),frac:PhantomData};
diff --git a/fixed_wide/src/tests.rs b/fixed_wide/src/tests.rs
index 05c911a..a46ef87 100644
--- a/fixed_wide/src/tests.rs
+++ b/fixed_wide/src/tests.rs
@@ -31,16 +31,26 @@ fn find_equiv_sqrt_via_f64(n:I32F32)->I32F32{
 	let ibits=bits as i64;
 	let f=(ibits as f64)/((1u64<<32) as f64);
 	let f_ans=f.sqrt();
-	let mut i=(f_ans*((1u64<<32) as f64)) as i64;
-	let s=(i as i128)*(i as i128);
-	if s<((ibits as i128)<<32){
-		i+=1;
+	let i=(f_ans*((1u64<<32) as f64)) as i64;
+	let r=I32F32::from_bits(bnum::BInt::<1>::from(i));
+	//mimic the behaviour of the algorithm,
+	//return the result if it truncates to the exact answer
+	if (r+I32F32::EPSILON)*(r+I32F32::EPSILON)==n{
+		return r+I32F32::EPSILON;
 	}
-	I32F32::from_bits(bnum::BInt::<1>::from(i))
+	if (r-I32F32::EPSILON)*(r-I32F32::EPSILON)==n{
+		return r-I32F32::EPSILON;
+	}
+	return r;
+}
+fn test_exact(n:I32F32){
+	assert_eq!(n.sqrt(),find_equiv_sqrt_via_f64(n));
 }
 #[test]
 fn test_sqrt_exact(){
-	let a=I32F32::ONE*2;
-	let b=find_equiv_sqrt_via_f64(a);
-	assert_eq!(a.sqrt(),b);
+	//43
+	for i in 0..((i64::MAX as f32).ln() as u32){
+		let n=I32F32::from_bits(bnum::BInt::<1>::from((i as f32).exp() as i64));
+		test_exact(n);
+	}
 }