diff --git a/res/layout/calc_clear_button.xml b/res/layout/calc_clear_button.xml
index da1af738..3fd23042 100644
--- a/res/layout/calc_clear_button.xml
+++ b/res/layout/calc_clear_button.xml
@@ -9,6 +9,7 @@
 <org.solovyev.android.view.widgets.ColorButton xmlns:a="http://schemas.android.com/apk/res/android"
 			 xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
 			 a:id="@+id/clearButton"
-			 a:drawableTop="@drawable/ic_delete"
+			 a:text="@string/c_clear"
+			 a:textStyle="bold"
 			 style="@style/control_image_button_style"
 			 a:onClick="clearButtonClickHandler"/>
\ No newline at end of file
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 37992ffe..682052b0 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -29,7 +29,7 @@
 
 	<string name="c_undo">undo</string>
 	<string name="c_redo">redo</string>
-	<string name="c_clear">clear all</string>
+	<string name="c_clear">CE</string>
 	<string name="c_erase">clear</string>
 	<string name="c_paste">paste</string>
 	<string name="c_vars">vars</string>
diff --git a/src/main/java/org/solovyev/android/calculator/model/CalculatorModel.java b/src/main/java/org/solovyev/android/calculator/model/CalculatorModel.java
index 354cde40..1ca8030d 100644
--- a/src/main/java/org/solovyev/android/calculator/model/CalculatorModel.java
+++ b/src/main/java/org/solovyev/android/calculator/model/CalculatorModel.java
@@ -14,6 +14,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.JsclOperation;
 import org.solovyev.common.NumberMapper;
+import org.solovyev.common.utils.MutableObject;
 
 /**
  * User: serso
diff --git a/src/test/java/org/solovyev/android/calculator/model/CalculatorModelTest.java b/src/test/java/org/solovyev/android/calculator/model/CalculatorModelTest.java
index 5cd55a20..21dc24c9 100644
--- a/src/test/java/org/solovyev/android/calculator/model/CalculatorModelTest.java
+++ b/src/test/java/org/solovyev/android/calculator/model/CalculatorModelTest.java
@@ -48,6 +48,7 @@ public class CalculatorModelTest {
 		Assert.assertEquals("-2.0+2.1i", cm.evaluate(JsclOperation.numeric, "-2+2.1i"));
 		Assert.assertEquals("-3.41007+3.41007i", cm.evaluate(JsclOperation.numeric, "(5tan(2i)+2i)/(1-i)"));
 		Assert.assertEquals("-0.1-0.2i", cm.evaluate(JsclOperation.numeric, "(1-i)/(2+6i)"));
+		//Assert.assertEquals("-0.1-0.2i", cm.evaluate(JsclOperation.numeric, "cos(cos(cos(cos(acos(acos(acos(acos(acos(acos(acos(acos(cos(cos(cos(cos(cosh(acos(cos()))))))))))))))))))"));
 
 		CalculatorModel.instance.getVarsRegister().addVar(null, new Var.Builder("si", 5d));
 		Assert.assertEquals("5.0", cm.evaluate(JsclOperation.numeric, "si"));