diff -r a0505844750a -r 2377bb30dd1b vm/src/test/java/org/apidesign/vm4brwsr/NumberTest.java
--- a/vm/src/test/java/org/apidesign/vm4brwsr/NumberTest.java	Tue Oct 16 18:04:11 2012 +0200
+++ b/vm/src/test/java/org/apidesign/vm4brwsr/NumberTest.java	Tue Oct 30 23:33:29 2012 +0100
@@ -19,8 +19,8 @@
 
 import javax.script.Invocable;
 import javax.script.ScriptException;
+import static org.testng.Assert.*;
 import org.testng.annotations.BeforeClass;
-import static org.testng.Assert.*;
 import org.testng.annotations.Test;
 
 /**
@@ -45,6 +45,16 @@
             "3.3"
         );
     }
+    
+    @Test public void javalog1000() throws Exception {
+        assertEquals(3.0, Math.log10(1000.0), 0.00003, "log_10(1000) == 3");
+    }
+
+    @Test public void jslog1000() throws Exception {
+        assertExec("log_10(1000) == 3", "java_lang_Math_log10DD", 
+            Double.valueOf(3.0), 1000.0
+        );
+    }
 
     
     private static CharSequence codeSeq;
@@ -76,6 +86,12 @@
         if (expRes.equals(ret)) {
             return;
         }
+        if (expRes instanceof Double && ret instanceof Double) {
+            double expD = ((Double)expRes).doubleValue();
+            double retD = ((Double)ret).doubleValue();
+            assertEquals(retD, expD, 0.000004, msg + " was " + ret + "\n" + codeSeq);
+            return;
+        }
         assertEquals(ret, expRes, msg + "was: " + ret + "\n" + codeSeq);
     }