Do not use simplify in DivExpression::toString() and CompExpression::…

…toString()
fintarin · Feb 14, 2024 · 4a16b6c · 4a16b6c
1 parent 5916a36
commit 4a16b6c
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Showing 6 changed files with 43 additions and 12 deletions.
diff --git a/include/fintamath/expressions/ExpressionUtils.hpp b/include/fintamath/expressions/ExpressionUtils.hpp
@@ -74,6 +74,8 @@ std::pair<ArgumentPtr, ArgumentPtr> splitPowExpr(const ArgumentPtr &rhs);
 
 std::pair<ArgumentPtr, ArgumentPtr> splitRational(const ArgumentPtr &arg);
 
+ArgumentPtr negate(const ArgumentPtr &arg);
+
 ArgumentPtr makePolynom(const IFunction &func, ArgumentPtrVector &&args);
 
 ArgumentPtr makePolynom(const IFunction &func, const ArgumentPtrVector &args);

diff --git a/src/fintamath/expressions/ExpressionUtils.cpp b/src/fintamath/expressions/ExpressionUtils.cpp
@@ -223,6 +223,37 @@ std::pair<ArgumentPtr, ArgumentPtr> splitRational(const ArgumentPtr &arg) {
   return {arg, Integer(1).clone()};
 }
 
+ArgumentPtr negate(const ArgumentPtr &arg) {
+  if (const auto expr = cast<IExpression>(arg)) {
+    if (is<Add>(expr->getFunction())) {
+      auto negChildrenView =
+          expr->getChildren() |
+          stdv::transform([](const ArgumentPtr &child) {
+            return negate(child);
+          });
+      return makePolynom(Add{}, ArgumentPtrVector(negChildrenView.begin(), negChildrenView.end())); // TODO: use C++23 stdv::to
+    }
+
+    if (is<Mul>(expr->getFunction())) {
+      if (const auto firstChildNum = cast<INumber>(expr->getChildren().front())) {
+        if (*firstChildNum == Integer(-1)) {
+          ArgumentPtrVector negChildren(expr->getChildren().begin() + 1, expr->getChildren().end());
+          return makePolynom(Mul(), std::move(negChildren));
+        }
+
+        ArgumentPtrVector negChildren = expr->getChildren();
+        negChildren.front() = (*firstChildNum) * Integer(-1);
+        return makePolynom(Mul(), std::move(negChildren));
+      }
+    }
+  }
+  else if (const auto arithm = cast<IArithmetic>(arg)) {
+    return (*arithm) * Integer(-1);
+  }
+
+  return mulExpr(Integer(-1).clone(), arg);
+}
+
 ArgumentPtr makePolynom(const IFunction &func, ArgumentPtrVector &&args) {
   if (args.empty()) {
     return {};

diff --git a/src/fintamath/expressions/binary/CompExpression.cpp b/src/fintamath/expressions/binary/CompExpression.cpp
@@ -47,17 +47,12 @@ std::string CompExpression::toString() const {
         *lhsExpr->getFunction() == Add{}) {
 
       ArgumentPtrVector sumChildren = lhsExpr->getChildren();
-      const ArgumentPtr solLhs = sumChildren.front();
+      ArgumentPtr solLhs = sumChildren.front();
 
       if (is<Variable>(solLhs)) {
         sumChildren.erase(sumChildren.begin());
-
-        ArgumentPtr solRhs = negExpr(std::move(sumChildren));
-        simplifyChild(solRhs);
-
-        if (!is<IExpression>(solRhs)) {
-          return CompExpression(cast<IOperator>(*func), solLhs, solRhs).toString();
-        }
+        ArgumentPtr solRhs = detail::negate(makePolynom(Add{}, std::move(sumChildren)));
+        return CompExpression(cast<IOperator>(*func), std::move(solLhs), std::move(solRhs)).toString();
       }
     }
   }

diff --git a/src/fintamath/expressions/binary/DivExpression.cpp b/src/fintamath/expressions/binary/DivExpression.cpp
@@ -46,9 +46,8 @@ DivExpression::DivExpression(ArgumentPtr inLhsChild, ArgumentPtr inRhsChild)
 }
 
 std::string DivExpression::toString() const {
-  if (isNegated(lhsChild)) { // TODO! find more efficient solution
-    ArgumentPtr innerDiv = divExpr(negExpr(lhsChild)->toMinimalObject(), rhsChild);
-    return negExpr(std::move(innerDiv))->toString();
+  if (isNegated(lhsChild)) {
+    return negExpr(divExpr(detail::negate(lhsChild), rhsChild))->toString();
   }
 
   return IBinaryExpression::toString();

diff --git a/tests/src/expressions/ExpressionUtilsTests.cpp b/tests/src/expressions/ExpressionUtilsTests.cpp
@@ -124,3 +124,7 @@ TEST(ExpressionUtilsTests, isNegativeNumberTest) {
 TEST(ExpressionUtilsTests, makePolynomTest) {
   // TODO: implement
 }
+
+TEST(ExpressionUtilsTests, negateTest) {
+  // TODO: implement
+}
diff --git a/tests/src/overall/simplify/SimplifyDerivativeTests.cpp b/tests/src/overall/simplify/SimplifyDerivativeTests.cpp
@@ -282,7 +282,7 @@ TEST(SimplifyDerivativeTests, simplifyTest) {
   EXPECT_EQ(Expression("derivative(ln(cos(3x)), x)").toString(),
             "-3 tan(3 x)");
   EXPECT_EQ(Expression("derivative(log(sin(x^5), tan(x^3)), x)").toString(),
-            "(3 sec(x^3)^2 x^2 cos(x^3) csc(x^3))/ln(sin(x^5)) - (5 x^4 cot(x^5) ln(tan(x^3)))/(ln(sin(x^5))^2)");
+            "(3 sec(x^3)^2 x^2 cos(x^3) csc(x^3))/ln(sin(x^5)) - (5 x^4 cos(x^5) csc(x^5) ln(tan(x^3)))/(ln(sin(x^5))^2)");
   EXPECT_EQ(Expression("derivative(acos(4x + 5)^5, x)").toString(),
             "-(20 acos(4 x + 5)^4)/sqrt(-16 x^2 - 40 x - 24)");
   EXPECT_EQ(Expression("derivative(sin(sin(sin(x))), x)").toString(),