Added a default linear model for line datation.

rugged-api/src/main/java/org/orekit/rugged/api/LineDatation.java

@@ -17,6 +17,7 @@
 package org.orekit.rugged.api;
 
 /** Interface representing line datation model.
+ * @see LinearLineDatation
  * @author Luc Maisonobe
  */
 public interface LineDatation {

rugged-api/src/main/java/org/orekit/rugged/api/LinearLineDatation.java

+/* Copyright 2013-2014 CS Systèmes d'Information
+ * Licensed to CS Systèmes d'Information (CS) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * CS licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.orekit.rugged.api;
+
+
+/** Linear model for {@link LineDatation line datation}.
+ * <p>
+ * Instances of this class are guaranteed to be immutable.
+ * </p>
+ * @author Luc Maisonobe
+ */
+public class LinearLineDatation implements LineDatation {
+
+    /** Line number at reference date. */
+    private final double line0;
+
+    /** Rate of lines scanning (lines / seconds). */
+    private final double rate;
+
+    /** Simple constructor
+     * @param line0 line number at reference date
+     * @param rate rate of lines scanning (lines / seconds)
+     */
+    public LinearLineDatation(final double line0, final double rate) {
+        this.line0 = line0;
+        this.rate  = rate;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public double getDate(double lineNumber) {
+        return (lineNumber - line0) / rate;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public double getLine(double date) {
+        return line0 + rate * date;
+    }
+
+}