From 35ebf781dfc4a1f9e8da71755d22d67dfdf64a52 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Fri, 13 Oct 2017 15:47:24 +0200
Subject: [PATCH] [poincare] Fix bug in Cosine::immediateSimplify

Change-Id: Ib3fe9c99de1d8e83c7bebd7a28d546b275c0ceba
---
 poincare/src/cosine.cpp         | 22 ++++++++++++----------
 poincare/test/simplify_easy.cpp |  4 ++--
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/poincare/src/cosine.cpp b/poincare/src/cosine.cpp
index 5d8bcfdfa..8eacccca6 100644
--- a/poincare/src/cosine.cpp
+++ b/poincare/src/cosine.cpp
@@ -4,6 +4,7 @@
 #include <poincare/symbol.h>
 #include <poincare/rational.h>
 #include <poincare/trigonometry.h>
+#include <poincare/multiplication.h>
 #include <ion.h>
 extern "C" {
 #include <assert.h>
@@ -22,11 +23,9 @@ Expression * Cosine::clone() const {
 }
 
 Expression * Cosine::immediateSimplify() {
-  if (operand(0)->type() == Type::Rational && static_cast<const Rational *>(operand(0))->isZero()) {
-    return replaceWith(new Rational(Integer(1)), true);
-      }
-  if (operand(0)->type() == Type::Symbol && static_cast<const Symbol *>(operand(0))->name() == Ion::Charset::SmallPi) {
-    return replaceWith(new Rational(Integer(0)), true);
+  Expression * lookup = Trigonometry::table(operand(0), Trigonometry::Function::Cosine, false);
+  if (lookup != nullptr) {
+    return replaceWith(lookup, true);
   }
   if (operand(0)->sign() < 0) {
     ((Expression *)operand(0))->turnIntoPositive();
@@ -40,14 +39,17 @@ Expression * Cosine::immediateSimplify() {
       Rational * newR = new Rational(div.remainder, r->denominator());
       const_cast<Expression *>(operand(0))->replaceOperand(r, newR, true);
       const_cast<Expression *>(operand(0))->immediateSimplify();
-      return immediateSimplify(); // recursive
+      if (Integer::Division(div.quotient, Integer(2)).remainder.isOne()) {
+        Expression * simplifiedCosine = immediateSimplify(); // recursive
+        const Expression * multOperands[2] = {new Rational(Integer(-1)), simplifiedCosine->clone()};
+        Multiplication * m = new Multiplication(multOperands, 2, false);
+        return simplifiedCosine->replaceWith(m, true)->immediateSimplify();
+      } else {
+        return immediateSimplify(); // recursive
+      }
     }
     assert(r->sign() > 0);
     assert(r->numerator().isLowerThan(r->denominator()));
-    Expression * lookup = Trigonometry::table(operand(0), Trigonometry::Function::Cosine, false);
-    if (lookup != nullptr) {
-      return replaceWith(lookup, true);
-    }
   }
   return this;
 }
diff --git a/poincare/test/simplify_easy.cpp b/poincare/test/simplify_easy.cpp
index adb969c82..6a7aaca35 100644
--- a/poincare/test/simplify_easy.cpp
+++ b/poincare/test/simplify_easy.cpp
@@ -144,11 +144,11 @@ QUIZ_CASE(poincare_simplify_easy) {
   assert_parsed_expression_simplify_to("(1+R(2))/5", "(1+R(2))/5"); // TODO: put 5 on denominator?
   assert_parsed_expression_simplify_to("(2+R(6))^2", "(2+R(6))^2"); // Check for parenthesis
   assert_parsed_expression_simplify_to("cos(0)", "1");
-  assert_parsed_expression_simplify_to("cos(P)", "0");
+  assert_parsed_expression_simplify_to("cos(P)", "-1");
   assert_parsed_expression_simplify_to("cos(P*35/29)", "cos(P*6/29)");
   assert_parsed_expression_simplify_to("cos(-P*35/29)", "cos(P*6/29)");
   assert_parsed_expression_simplify_to("cos(P*340000)", "1");
-  assert_parsed_expression_simplify_to("cos(-P*340000)", "1");
+  assert_parsed_expression_simplify_to("cos(-P*340001)", "-1");
   assert_parsed_expression_simplify_to("cos(P/12)", "(R(6)+R(2))/4");
   assert_parsed_expression_simplify_to("cos(-P/12)", "(R(6)+R(2))/4");
   assert_parsed_expression_simplify_to("cos(-P*R(2))", "cos(P*R(2))");