From ae30889bbba139ed49a3a848170e1514efcec29d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20M=C3=BCller?= <stefan.mueller@aksdb.de>
Date: Sat, 25 May 2024 02:50:24 +0200
Subject: [PATCH] Fixed calculation of root-isolating intervals and tests

---
 UPolynomialRoots.pas                | 8 ++++----
 tests/UPolynomialRootsTestCases.pas | 8 +++++---
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/UPolynomialRoots.pas b/UPolynomialRoots.pas
index b2636f8..3d9fafa 100644
--- a/UPolynomialRoots.pas
+++ b/UPolynomialRoots.pas
@@ -28,8 +28,8 @@ type
 
   { TIsolatingInterval }
 
-  // Represents an isolating interval of the form [C / 2^K, (C + H) / 2^K] in respect to [0, 1] or [A / 2^K, B / 2^K] in
-  // respect to [0, bound], with A = C * bound and B = (C + H) * bound.
+  // Represents an isolating interval of the form [C / 2^K, (C + H) / 2^K] in respect to [0, 1] or [A, B] in respect to
+  // [0, bound], with A = C * bound / 2^K and B = (C + H) * bound / 2^K.
   TIsolatingInterval = record
     C, K, H: Cardinal;
     Bound, A, B: TBigInt;
@@ -82,8 +82,8 @@ begin
   Result.K := AK;
   Result.H := AH;
   Result.Bound := ABound;
-  Result.A := AC * ABound;
-  Result.B := (AC + AH) * ABound;
+  Result.A := (AC * ABound) >> AK;
+  Result.B := ((AC + AH) * ABound) >> AK;
 end;
 
 function TRootIsolation.Bisect(constref APolynomial: TBigIntPolynomial): TIsolatingIntervals;
diff --git a/tests/UPolynomialRootsTestCases.pas b/tests/UPolynomialRootsTestCases.pas
index 3ae8ffe..e1d765d 100644
--- a/tests/UPolynomialRootsTestCases.pas
+++ b/tests/UPolynomialRootsTestCases.pas
@@ -49,20 +49,22 @@ procedure TPolynomialRootsTestCase.AssertBisectResult(constref AIsolatingInterva
   AExpectedRoots: array of Cardinal);
 var
   exp: Cardinal;
-  ri: TIsolatingInterval;
   found: Boolean;
+  i, foundIndex: Integer;
 begin
   AssertEquals('Unexpected number of isolating intervals.', Length(AExpectedRoots), AIsolatingIntervals.Count);
   for exp in AExpectedRoots do
   begin
     found := False;
-    for ri in AIsolatingIntervals do
-      if (ri.A <= exp) and (exp <= ri.B) then
+    for i := 0 to AIsolatingIntervals.Count - 1 do
+      if (AIsolatingIntervals[i].A <= exp) and (exp <= AIsolatingIntervals[i].B) then
       begin
         found := True;
+        foundIndex := i;
         Break;
       end;
     AssertTrue('No isolating interval for expected root ' + IntToStr(exp) + ' found.', found);
+    AIsolatingIntervals.Delete(foundIndex);
   end;
 end;