diff --git a/src/main/java/de/neemann/digital/hdl/hgs/Context.java b/src/main/java/de/neemann/digital/hdl/hgs/Context.java
index 2d891ced2..b6a32b367 100644
--- a/src/main/java/de/neemann/digital/hdl/hgs/Context.java
+++ b/src/main/java/de/neemann/digital/hdl/hgs/Context.java
@@ -12,6 +12,7 @@ import de.neemann.digital.lang.Lang;
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Locale;
 
 /**
  * The evaluation context
@@ -254,7 +255,7 @@ public class Context {
         for (int i = 1; i < args.size(); i++)
             eval.add(args.get(i).value(c));
 
-        return String.format(Value.toString(args.get(0).value(c)), eval.toArray());
+        return String.format(Locale.US, Value.toString(args.get(0).value(c)), eval.toArray());
     }
 
     private static final class FunctionIsPresent extends InnerFunction {
diff --git a/src/main/java/de/neemann/digital/hdl/hgs/Parser.java b/src/main/java/de/neemann/digital/hdl/hgs/Parser.java
index b4f59f8e4..3789d3e9b 100644
--- a/src/main/java/de/neemann/digital/hdl/hgs/Parser.java
+++ b/src/main/java/de/neemann/digital/hdl/hgs/Parser.java
@@ -70,7 +70,7 @@ public class Parser {
     /**
      * Creates a new instance
      *
-     * @param reader the reader to parse
+     * @param reader  the reader to parse
      * @param srcFile the source file name if any
      */
     public Parser(Reader reader, String srcFile) {
@@ -323,6 +323,14 @@ public class Parser {
         }
     }
 
+    private double convToDouble(String num) throws ParserException {
+        try {
+            return Double.parseDouble(num);
+        } catch (NumberFormatException e) {
+            throw newParserException("not a number: " + tok.getIdent());
+        }
+    }
+
     private ParserException newUnexpectedToken(Tokenizer.Token token) {
         String name = token == IDENT ? tok.getIdent() : token.name();
         return newParserException("unexpected Token: " + name);
@@ -356,13 +364,13 @@ public class Parser {
                 case NOTEQUAL:
                     return c -> !Value.equals(a.value(c), b.value(c));
                 case LESS:
-                    return c -> Value.toLong(a.value(c)) < Value.toLong(b.value(c));
+                    return c -> Value.less(a.value(c), b.value(c));
                 case LESSEQUAL:
-                    return c -> Value.toLong(a.value(c)) <= Value.toLong(b.value(c));
+                    return c -> Value.lessEqual(a.value(c), b.value(c));
                 case GREATER:
-                    return c -> Value.toLong(a.value(c)) > Value.toLong(b.value(c));
+                    return c -> Value.less(b.value(c), a.value(c));
                 case GREATEREQUAL:
-                    return c -> Value.toLong(a.value(c)) >= Value.toLong(b.value(c));
+                    return c -> Value.lessEqual(b.value(c), a.value(c));
                 default:
                     throw newUnexpectedToken(t);
             }
@@ -435,7 +443,7 @@ public class Parser {
         while (nextIs(SUB)) {
             Expression a = ac;
             Expression b = parseMul();
-            ac = c -> Value.toLong(a.value(c)) - Value.toLong(b.value(c));
+            ac = c -> Value.sub(a.value(c), b.value(c));
         }
         return ac;
     }
@@ -445,7 +453,7 @@ public class Parser {
         while (nextIs(MUL)) {
             Expression a = ac;
             Expression b = parseDiv();
-            ac = c -> Value.toLong(a.value(c)) * Value.toLong(b.value(c));
+            ac = c -> Value.mul(a.value(c), b.value(c));
         }
         return ac;
     }
@@ -455,7 +463,7 @@ public class Parser {
         while (nextIs(DIV)) {
             Expression a = ac;
             Expression b = parseMod();
-            ac = c -> Value.toLong(a.value(c)) / Value.toLong(b.value(c));
+            ac = c -> Value.div(a.value(c), b.value(c));
         }
         return ac;
     }
@@ -480,6 +488,9 @@ public class Parser {
             case NUMBER:
                 long num = convToLong(tok.getIdent());
                 return c -> num;
+            case DOUBLE:
+                double d = convToDouble(tok.getIdent());
+                return c -> d;
             case STRING:
                 String s = tok.getIdent();
                 return c -> s;
diff --git a/src/main/java/de/neemann/digital/hdl/hgs/Tokenizer.java b/src/main/java/de/neemann/digital/hdl/hgs/Tokenizer.java
index 1cfdc42cf..2bde538e6 100644
--- a/src/main/java/de/neemann/digital/hdl/hgs/Tokenizer.java
+++ b/src/main/java/de/neemann/digital/hdl/hgs/Tokenizer.java
@@ -18,7 +18,7 @@ class Tokenizer {
         UNKNOWN, IDENT, AND, OR, XOR, NOT, OPEN, CLOSE, NUMBER, EOL, EOF, SHIFTLEFT, SHIFTRIGHT, COMMA, EQUAL,
         ADD, SUB, MUL, GREATER, LESS, DIV, MOD, END, IF, ELSE, FOR, WHILE, SEMICOLON, NOTEQUAL, STRING,
         OPENBRACE, CLOSEDBRACE, CODEEND, OPENSQUARE, CLOSEDSQUARE, DOT, STATIC, FUNC, GREATEREQUAL, LESSEQUAL,
-        REPEAT, RETURN, COLON, UNTIL
+        REPEAT, RETURN, COLON, UNTIL, DOUBLE
     }
 
     private static HashMap<String, Token> statementMap = new HashMap<>();
@@ -275,6 +275,9 @@ class Tokenizer {
             c = readChar();
             if (isNumberChar(c) || isHexChar(c) || c == 'x' || c == 'X') {
                 builder.append((char) c);
+            } else if (c == '.') {
+                builder.append((char) c);
+                token = Token.DOUBLE;
             } else {
                 unreadChar(c);
                 wasChar = false;
diff --git a/src/main/java/de/neemann/digital/hdl/hgs/Value.java b/src/main/java/de/neemann/digital/hdl/hgs/Value.java
index f9a843e96..15f6893c1 100644
--- a/src/main/java/de/neemann/digital/hdl/hgs/Value.java
+++ b/src/main/java/de/neemann/digital/hdl/hgs/Value.java
@@ -123,7 +123,9 @@ public final class Value {
      * @return true if both values are equal
      */
     public static boolean equals(Object a, Object b) {
-        if (a instanceof Number && b instanceof Number)
+        if (a instanceof Double || b instanceof Double)
+            return a.equals(b);
+        else if (a instanceof Number && b instanceof Number)
             return ((Number) a).longValue() == ((Number) b).longValue();
         else if (a instanceof String || b instanceof String)
             return a.toString().equals(b.toString());
@@ -140,6 +142,8 @@ public final class Value {
      * @throws HGSEvalException HGSEvalException
      */
     public static Object add(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) + toDouble(b);
         if (a instanceof Number && b instanceof Number)
             return ((Number) a).longValue() + ((Number) b).longValue();
         if (a instanceof String || b instanceof String)
@@ -147,6 +151,54 @@ public final class Value {
         throw new HGSEvalException("arguments must be int or string, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
     }
 
+    /**
+     * Subtracts two values
+     *
+     * @param a a value
+     * @param b a value
+     * @return the sum
+     * @throws HGSEvalException HGSEvalException
+     */
+    public static Object sub(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) - toDouble(b);
+        if (a instanceof Number && b instanceof Number)
+            return ((Number) a).longValue() - ((Number) b).longValue();
+        throw new HGSEvalException("arguments must be int or double, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
+    }
+
+    /**
+     * Multiplies two values
+     *
+     * @param a a value
+     * @param b a value
+     * @return the product
+     * @throws HGSEvalException HGSEvalException
+     */
+    public static Object mul(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) * toDouble(b);
+        if (a instanceof Number && b instanceof Number)
+            return ((Number) a).longValue() * ((Number) b).longValue();
+        throw new HGSEvalException("arguments must be int or double, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
+    }
+
+    /**
+     * Divides two numbers
+     *
+     * @param a a value
+     * @param b a value
+     * @return the quotient
+     * @throws HGSEvalException HGSEvalException
+     */
+    public static Object div(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) / toDouble(b);
+        if (a instanceof Number && b instanceof Number)
+            return ((Number) a).longValue() / ((Number) b).longValue();
+        throw new HGSEvalException("arguments must be int or double, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
+    }
+
     /**
      * Performs an or operation
      *
@@ -202,6 +254,42 @@ public final class Value {
         return !toBool(value);
     }
 
+    /**
+     * Helper compare two values
+     *
+     * @param a a value
+     * @param b a value
+     * @return true if a&lt;b
+     * @throws HGSEvalException HGSEvalException
+     */
+    public static boolean less(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) < toDouble(b);
+        if (a instanceof Number && b instanceof Number)
+            return toLong(a) < toLong(b);
+        if (a instanceof String && b instanceof String)
+            return a.toString().compareTo(b.toString()) < 0;
+        throw new HGSEvalException("arguments must be int, double or string, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
+    }
+
+    /**
+     * Helper compare two values
+     *
+     * @param a a value
+     * @param b a value
+     * @return true if a<=b
+     * @throws HGSEvalException HGSEvalException
+     */
+    public static boolean lessEqual(Object a, Object b) throws HGSEvalException {
+        if (a instanceof Double || b instanceof Double)
+            return toDouble(a) <= toDouble(b);
+        if (a instanceof Number && b instanceof Number)
+            return toLong(a) <= toLong(b);
+        if (a instanceof String && b instanceof String)
+            return a.toString().compareTo(b.toString()) <= 0;
+        throw new HGSEvalException("arguments must be int, double or string, not " + a.getClass().getSimpleName() + "+" + b.getClass().getSimpleName());
+    }
+
     /**
      * Trims spaces at the right side of the string.
      *
diff --git a/src/test/java/de/neemann/digital/hdl/hgs/ParserTest.java b/src/test/java/de/neemann/digital/hdl/hgs/ParserTest.java
index a5e9139c5..0132885b2 100644
--- a/src/test/java/de/neemann/digital/hdl/hgs/ParserTest.java
+++ b/src/test/java/de/neemann/digital/hdl/hgs/ParserTest.java
@@ -78,6 +78,21 @@ public class ParserTest extends TestCase {
         assertEquals("Hallo_true", new Parser("\"Hallo_\" + (1<2)").parseExp().value(new Context()));
     }
 
+    public void testParseExpArithDouble() throws IOException, ParserException, HGSEvalException {
+        assertEquals(4.0, new Parser("1.5+2.5").parseExp().value(new Context()));
+        assertEquals(0.5, new Parser("1.5-1").parseExp().value(new Context()));
+        assertEquals(3.0, new Parser("1.5*2").parseExp().value(new Context()));
+        assertEquals(3.0, new Parser("2*1.5").parseExp().value(new Context()));
+        assertEquals(1L, new Parser("3/2").parseExp().value(new Context()));
+        assertEquals(1.5, new Parser("3.0/2").parseExp().value(new Context()));
+        assertEquals(1.5, new Parser("3/2.0").parseExp().value(new Context()));
+        assertEquals(1.5, new Parser("3.0/2.0").parseExp().value(new Context()));
+        assertEquals(true, new Parser("1.0001>1").parseExp().value(new Context()));
+        assertEquals(false, new Parser("1>1.0001").parseExp().value(new Context()));
+        assertEquals(false, new Parser("1.0001<1").parseExp().value(new Context()));
+        assertEquals(true, new Parser("1<1.0001").parseExp().value(new Context()));
+    }
+
     public void testParseExpCompare() throws IOException, ParserException, HGSEvalException {
         assertEquals(true, new Parser("5=5").parseExp().value(new Context()));
         assertEquals(true, new Parser("\"Hello\"=\"Hello\"").parseExp().value(new Context()));
@@ -85,6 +100,10 @@ public class ParserTest extends TestCase {
         assertEquals(false, new Parser("5!=5").parseExp().value(new Context()));
         assertEquals(false, new Parser("\"Hello\"!=\"Hello\"").parseExp().value(new Context()));
         assertEquals(true, new Parser("\"Hello\"!=\"World\"").parseExp().value(new Context()));
+        assertEquals(true, new Parser("\"a\"<\"b\"").parseExp().value(new Context()));
+        assertEquals(false, new Parser("\"b\"<\"a\"").parseExp().value(new Context()));
+        assertEquals(false, new Parser("\"a\">\"b\"").parseExp().value(new Context()));
+        assertEquals(true, new Parser("\"b\">\"a\"").parseExp().value(new Context()));
 
         assertEquals(false, new Parser("5<5").parseExp().value(new Context()));
         assertEquals(true, new Parser("4<5").parseExp().value(new Context()));
@@ -265,6 +284,10 @@ public class ParserTest extends TestCase {
         Context c = new Context().declareVar("Bits", 17);
         exec("<? a:=format(\"hex=%x;\",Bits); print(a);?>", c);
         assertEquals("hex=11;", c.toString());
+
+        c = new Context().declareVar("freq", Math.PI*100);
+        exec("<? a:=format(\"f=%.2f;\",freq); print(a);?>", c);
+        assertEquals("f=314.16;", c.toString());
     }
 
     public void testComment() throws IOException, ParserException, HGSEvalException {