Added interface for multivariate online regression

java/com.sap.sailing.polars/src/com/sap/sailing/polars/regression/OnlineMultiVariateRegression.java

@@ -0,0 +1,26 @@
+package com.sap.sailing.polars.regression;
+
+public interface OnlineMultiVariateRegression {
+    
+    /**
+     * Adds data to the regression. This will change the weights.
+     * 
+     * @param y
+     * @param x
+     *            length of the array needs to be the dimension of the regression (depending on the implementation, the
+     *            dimension could be configured in the constructor), else IllegalArgumentsException will be thrown
+     */
+    void addData(double y, double[] x);
+    
+    /**
+     * After adding some data with {@link #addData(double, double[])} this method can be used to estimate y for any
+     * x-vector.
+     * 
+     * @param x
+     *            length of the array needs to be the dimension of the regression (depending on the implementation, the
+     *            dimension could be configured in the constructor), else IllegalArgumentsException will be thrown
+     * @return
+     */
+    double estimateY(double[] x);
+
+}