diff --git a/src/app/core/vtranslation.h b/src/app/core/vtranslation.h
index edcd3b3a8..96e997c47 100644
--- a/src/app/core/vtranslation.h
+++ b/src/app/core/vtranslation.h
@@ -38,7 +38,7 @@
  * I took idea from this article http://ololoepepe.blogspot.com/2013/08/qt.html.
  * As you know, if wrap string to a function translate, it will be marked for translation. No matter what namespace
  * contains this function. In class Translation used this circumstance.
- * It is mean never change name of method translate!!!!!.
+ * This mean never change name of method translate!!!!!.
  * Instead of using QT_TRANSLATE_NOOP3 macros we can store strings in QMap.
  * Example:
  * create map and fill up its
diff --git a/src/app/dialogs/app/configpages/configurationpage.cpp b/src/app/dialogs/app/configpages/configurationpage.cpp
index 8e1d13bca..4cc4e01de 100644
--- a/src/app/dialogs/app/configpages/configurationpage.cpp
+++ b/src/app/dialogs/app/configpages/configurationpage.cpp
@@ -86,8 +86,8 @@ void ConfigurationPage::Apply()
         QString locale = qvariant_cast<QString>(langCombo->itemData(langCombo->currentIndex()));
         qApp->getSettings()->setValue("configuration/locale", locale);
         langChanged = false;
-        QString text = QString(tr("Setup user interface language updated and will be used the next time start") + " " +
-                               QApplication::applicationName());
+        QString text = tr("Setup user interface language updated and will be used the next time start") + " " +
+                          QApplication::applicationName();
         QMessageBox::information(this, QApplication::applicationName(), text);
     }
     if (this->unitChanged)
@@ -95,7 +95,7 @@ void ConfigurationPage::Apply()
         QString unit = qvariant_cast<QString>(this->unitCombo->itemData(this->unitCombo->currentIndex()));
         qApp->getSettings()->setValue("configuration/unit", unit);
         this->unitChanged = false;
-        QString text = QString(tr("Default unit updated and will be used the next pattern creation"));
+        QString text = tr("Default unit updated and will be used the next pattern creation");
         QMessageBox::information(this, QApplication::applicationName(), text);
     }
     if (labelLangChanged)
diff --git a/src/app/dialogs/app/dialoghistory.cpp b/src/app/dialogs/app/dialoghistory.cpp
index 81ff33926..78b7c6d96 100644
--- a/src/app/dialogs/app/dialoghistory.cpp
+++ b/src/app/dialogs/app/dialoghistory.cpp
@@ -201,7 +201,7 @@ QString DialogHistory::Record(const VToolRecord &tool)
     if (domElem.isElement() == false)
     {
         qDebug()<<"Can't find element by id"<<Q_FUNC_INFO;
-        return QString(tr("Can't create record."));
+        return tr("Can't create record.");
     }
     try
     {
@@ -291,7 +291,7 @@ QString DialogHistory::Record(const VToolRecord &tool)
                 else
                 {
                     qDebug()<<"Not enough points in splinepath"<<Q_FUNC_INFO;
-                    return QString(tr("Can't create record."));
+                    return tr("Can't create record.");
                 }
                 return record;
             }
@@ -397,14 +397,14 @@ QString DialogHistory::Record(const VToolRecord &tool)
                 break;
             default:
                 qDebug()<<"Got wrong tool type. Ignore.";
-                return QString(tr("Can't create record."));
+                return tr("Can't create record.");
                 break;
         }
     }
     catch (const VExceptionBadId &e)
     {
         qDebug()<<e.ErrorMessage()<<Q_FUNC_INFO;
-        return QString(tr("Can't create record."));
+        return tr("Can't create record.");
     }
     return QString();
 }
diff --git a/src/app/dialogs/app/dialogpatternxmledit.cpp b/src/app/dialogs/app/dialogpatternxmledit.cpp
index afd673bdb..6339ff47c 100644
--- a/src/app/dialogs/app/dialogpatternxmledit.cpp
+++ b/src/app/dialogs/app/dialogpatternxmledit.cpp
@@ -458,7 +458,7 @@ void DialogPatternXmlEdit::ButtonApplyChangesClicked()
                 Changes += currentChange->element->GettreeNodeName();
                 Changes += "/";
                 Changes += (currentChange->element->GettreeNodeValueSet()) ?
-                            currentChange->element->GettreeNodeValue(): QString(tr("<no value>"));
+                            currentChange->element->GettreeNodeValue(): tr("<no value>");
                 Changes += "\n";
             }
             else
@@ -466,9 +466,9 @@ void DialogPatternXmlEdit::ButtonApplyChangesClicked()
                 if (currentChange->type == DialogPatternXmlEdit::ChangeTypeModify)
                 {
                     Changes += QString("Modified type %1 : ").arg(nodetype);
-                    Changes += (currentChange->changedText) ? *currentChange->newText : QString(tr("Unchanged"));
+                    Changes += (currentChange->changedText) ? *currentChange->newText : tr("Unchanged");
                     Changes += "/";
-                    Changes += (currentChange->changedValue) ? *currentChange->newValue: QString(tr("Unchanged"));
+                    Changes += (currentChange->changedValue) ? *currentChange->newValue: tr("Unchanged");
                     Changes += "\n";
                 }
                 else
@@ -479,7 +479,7 @@ void DialogPatternXmlEdit::ButtonApplyChangesClicked()
                         Changes += currentChange->element->GettreeNodeName();
                         Changes += "/";
                         Changes += (currentChange->element->GettreeNodeValueSet()) ?
-                                    currentChange->element->GettreeNodeValue(): QString(tr("<no value>"));
+                                    currentChange->element->GettreeNodeValue(): tr("<no value>");
                         Changes += "\n";
                     }
                 }
diff --git a/src/app/dialogs/tools/dialogarc.cpp b/src/app/dialogs/tools/dialogarc.cpp
index 31671ed08..9d0293416 100644
--- a/src/app/dialogs/tools/dialogarc.cpp
+++ b/src/app/dialogs/tools/dialogarc.cpp
@@ -47,7 +47,7 @@ DialogArc::DialogArc(const VContainer *data, const quint32 &toolId, QWidget *par
     :DialogTool(data, toolId, parent), ui(new Ui::DialogArc), flagRadius(false), flagF1(false), flagF2(false),
       timerRadius(nullptr), timerF1(nullptr), timerF2(nullptr), center(NULL_ID), radius(QString()),
       f1(QString()), f2(QString()), formulaBaseHeight(0), formulaBaseHeightF1(0), formulaBaseHeightF2(0), path(nullptr),
-      angleF1(0), angleF2(0)
+      angleF1(INT_MIN), angleF2(INT_MIN)
 {
     ui->setupUi(this);
 
@@ -352,7 +352,17 @@ void DialogArc::EvalRadius()
 {
     labelEditFormula = ui->labelEditRadius;
     const QString postfix = VDomDocument::UnitsToStr(qApp->patternUnit(), true);
-    Eval(ui->plainTextEditFormula->toPlainText(), flagRadius, ui->labelResultRadius, postfix);
+    const qreal radius = Eval(ui->plainTextEditFormula->toPlainText(), flagRadius, ui->labelResultRadius, postfix);
+
+    if (radius < 0)
+    {
+        flagRadius = false;
+        ChangeColor(labelEditFormula, Qt::red);
+        ui->labelResultRadius->setText(tr("Error"));
+        ui->labelResultRadius->setToolTip(tr("Radius can't be negative"));
+
+        DialogArc::CheckState();
+    }
 }
 
 //---------------------------------------------------------------------------------------------------------------------
@@ -394,14 +404,21 @@ void DialogArc::ShowLineAngles()
 //---------------------------------------------------------------------------------------------------------------------
 void DialogArc::CheckAngles()
 {
+    if (angleF1 == INT_MIN || angleF2 == INT_MIN)
+    {
+        return;
+    }
+
     if (qFuzzyCompare(angleF1 + 1, angleF2 + 1))
     {
         flagF1 = false;
         ChangeColor(ui->labelEditF1, Qt::red);
+        ui->labelResultF1->setText(tr("Error"));
         ui->labelResultF1->setToolTip(tr("Angles equal"));
 
         flagF2 = false;
         ChangeColor(ui->labelEditF2, Qt::red);
+        ui->labelResultF2->setText(tr("Error"));
         ui->labelResultF2->setToolTip(tr("Angles equal"));
     }
 
diff --git a/src/app/dialogs/tools/dialogtool.cpp b/src/app/dialogs/tools/dialogtool.cpp
index e5942bc19..4d5264391 100644
--- a/src/app/dialogs/tools/dialogtool.cpp
+++ b/src/app/dialogs/tools/dialogtool.cpp
@@ -441,6 +441,7 @@ void DialogTool::ValFormulaChanged(bool &flag, QLineEdit *edit, QTimer *timer)
         CheckState();
         ChangeColor(labelEditFormula, Qt::red);
         labelResultCalculation->setText(tr("Error"));
+        labelResultCalculation->setToolTip(tr("Empty field"));
         return;
     }
     timer->start(1000);
@@ -458,6 +459,7 @@ void DialogTool::ValFormulaChanged(bool &flag, QPlainTextEdit *edit, QTimer *tim
         CheckState();
         ChangeColor(labelEditFormula, Qt::red);
         labelResultCalculation->setText(tr("Error"));
+        labelResultCalculation->setToolTip(tr("Empty field"));
         return;
     }
     timer->setSingleShot(true);
@@ -478,7 +480,7 @@ qreal DialogTool::Eval(const QString &text, bool &flag, QLabel *label, const QSt
     SCASSERT(label != nullptr);
     SCASSERT(labelEditFormula != nullptr);
 
-    qreal result = 0;
+    qreal result = INT_MIN;//Value can be 0, so use max imposible value
 
     if (text.isEmpty())
     {
@@ -908,7 +910,7 @@ void DialogTool::EvalFormula()
     SCASSERT(plainTextEditFormula != nullptr);
     SCASSERT(labelResultCalculation != nullptr);
     const QString postfix = VDomDocument::UnitsToStr(qApp->patternUnit());
-    Eval(plainTextEditFormula->toPlainText(), flagFormula, labelResultCalculation, postfix);
+    Eval(plainTextEditFormula->toPlainText(), flagFormula, labelResultCalculation, postfix, false);
 }
 
 //---------------------------------------------------------------------------------------------------------------------
diff --git a/src/app/tools/drawTools/vtoolarc.cpp b/src/app/tools/drawTools/vtoolarc.cpp
index 9ef6e70a1..5e245d2e3 100644
--- a/src/app/tools/drawTools/vtoolarc.cpp
+++ b/src/app/tools/drawTools/vtoolarc.cpp
@@ -214,10 +214,13 @@ void VToolArc::setFormulaRadius(const VFormula &value)
 {
     if (value.error() == false)
     {
-        QSharedPointer<VGObject> obj = VAbstractTool::data.GetGObject(id);
-        QSharedPointer<VArc> arc = qSharedPointerDynamicCast<VArc>(obj);
-        arc->SetFormulaRadius(value);
-        SaveOption(obj);
+        if (value.getDoubleValue() > 0)// Formula don't check this, but radius can't be 0 or negative
+        {
+            QSharedPointer<VGObject> obj = VAbstractTool::data.GetGObject(id);
+            QSharedPointer<VArc> arc = qSharedPointerDynamicCast<VArc>(obj);
+            arc->SetFormulaRadius(value);
+            SaveOption(obj);
+        }
     }
 }
 
@@ -241,8 +244,12 @@ void VToolArc::setFormulaF1(const VFormula &value)
     {
         QSharedPointer<VGObject> obj = VAbstractTool::data.GetGObject(id);
         QSharedPointer<VArc> arc = qSharedPointerDynamicCast<VArc>(obj);
-        arc->SetFormulaF1(value);
-        SaveOption(obj);
+
+        if (qFuzzyCompare(value.getDoubleValue() + 1, arc->GetF2() + 1)==false)// Angles can't be equal
+        {
+            arc->SetFormulaF1(value);
+            SaveOption(obj);
+        }
     }
 }
 
@@ -266,8 +273,11 @@ void VToolArc::setFormulaF2(const VFormula &value)
     {
         QSharedPointer<VGObject> obj = VAbstractTool::data.GetGObject(id);
         QSharedPointer<VArc> arc = qSharedPointerDynamicCast<VArc>(obj);
-        arc->SetFormulaF2(value);
-        SaveOption(obj);
+        if (qFuzzyCompare(value.getDoubleValue() + 1, arc->GetF1() + 1)==false)// Angles can't be equal
+        {
+            arc->SetFormulaF2(value);
+            SaveOption(obj);
+        }
     }
 }
 
diff --git a/src/app/visualization/vistoolsplinepath.cpp b/src/app/visualization/vistoolsplinepath.cpp
index e5e12a212..0fe4ff474 100644
--- a/src/app/visualization/vistoolsplinepath.cpp
+++ b/src/app/visualization/vistoolsplinepath.cpp
@@ -84,12 +84,12 @@ void VisToolSplinePath::RefreshGeometry()
         }
         if (path.CountPoint() < 3)
         {
-            Visualization::toolTip = QString(tr("<b>Curve path</b>: select three or more points"));
+            Visualization::toolTip = tr("<b>Curve path</b>: select three or more points");
         }
         else
         {
-            Visualization::toolTip = QString(tr("<b>Curve path</b>: select three or more points, "
-                                                "<b>Enter</b> - finish creation"));
+            Visualization::toolTip = tr("<b>Curve path</b>: select three or more points, "
+                                        "<b>Enter</b> - finish creation");
         }
     }
 }