diff --git a/src/main/java/org/apache/commons/math3/optimization/direct/BaseAbstractMultivariateVectorOptimizer.java b/src/main/java/org/apache/commons/math3/optimization/direct/BaseAbstractMultivariateVectorOptimizer.java
index 12958f9cb..c807f0cba 100644
--- a/src/main/java/org/apache/commons/math3/optimization/direct/BaseAbstractMultivariateVectorOptimizer.java
+++ b/src/main/java/org/apache/commons/math3/optimization/direct/BaseAbstractMultivariateVectorOptimizer.java
@@ -23,10 +23,15 @@ import org.apache.commons.math3.exception.TooManyEvaluationsException;
 import org.apache.commons.math3.exception.DimensionMismatchException;
 import org.apache.commons.math3.exception.NullArgumentException;
 import org.apache.commons.math3.analysis.MultivariateVectorFunction;
+import org.apache.commons.math3.optimization.OptimizationData;
+import org.apache.commons.math3.optimization.InitialGuess;
+import org.apache.commons.math3.optimization.Target;
+import org.apache.commons.math3.optimization.Weight;
 import org.apache.commons.math3.optimization.BaseMultivariateVectorOptimizer;
 import org.apache.commons.math3.optimization.ConvergenceChecker;
 import org.apache.commons.math3.optimization.PointVectorValuePair;
 import org.apache.commons.math3.optimization.SimpleVectorValueChecker;
+import org.apache.commons.math3.linear.RealMatrix;
 
 /**
  * Base class for implementing optimizers for multivariate scalar functions.
@@ -46,12 +51,16 @@ public abstract class BaseAbstractMultivariateVectorOptimizer<FUNC extends Multi
     private ConvergenceChecker<PointVectorValuePair> checker;
     /** Target value for the objective functions at optimum. */
     private double[] target;
-    /** Weight for the least squares cost computation. */
+    /** Weight matrix. */
+    private RealMatrix weightMatrix;
+    /** Weight for the least squares cost computation.
+     * @deprecated
+     */
     private double[] weight;
     /** Initial guess. */
     private double[] start;
     /** Objective function. */
-    private MultivariateVectorFunction function;
+    private FUNC function;
 
     /**
      * Simple constructor with default settings.
@@ -101,12 +110,46 @@ public abstract class BaseAbstractMultivariateVectorOptimizer<FUNC extends Multi
         return function.value(point);
     }
 
-    /** {@inheritDoc} */
+    /** {@inheritDoc}
+     *
+     * @deprecated As of 3.1. Please use
+     * {@link #optimize(int,MultivariateVectorFunction,OptimizationData[])}
+     * instead.
+     */
+    @Deprecated
     public PointVectorValuePair optimize(int maxEval, FUNC f, double[] t, double[] w,
                                          double[] startPoint) {
         return optimizeInternal(maxEval, f, t, w, startPoint);
     }
 
+    /**
+     * Optimize an objective function.
+     *
+     * @param maxEval Allowed number of evaluations of the objective function.
+     * @param f Objective function.
+     * @param optData Optimization data. The following data will be looked for:
+     * <ul>
+     *  <li>{@link Target}</li>
+     *  <li>{@link Weight}</li>
+     *  <li>{@link InitialGuess}</li>
+     * </ul>
+     * @return the point/value pair giving the optimal value of the objective
+     * function.
+     * @throws TooManyEvaluationsException if the maximal number of
+     * evaluations is exceeded.
+     * @throws DimensionMismatchException if the initial guess, target, and weight
+     * arguments have inconsistent dimensions.
+     *
+     * @since 3.1
+     */
+    protected PointVectorValuePair optimize(int maxEval,
+                                            FUNC f,
+                                            OptimizationData... optData)
+        throws TooManyEvaluationsException,
+               DimensionMismatchException {
+        return optimizeInternal(maxEval, f, optData);
+    }
+
     /**
      * Optimize an objective function.
      * Optimization is considered to be a weighted least-squares minimization.
@@ -126,8 +169,12 @@ public abstract class BaseAbstractMultivariateVectorOptimizer<FUNC extends Multi
      * if the maximal number of evaluations is exceeded.
      * @throws org.apache.commons.math3.exception.NullArgumentException if
      * any argument is {@code null}.
+     * @deprecated As of 3.1. Please use
+     * {@link #optimizeInternal(int,MultivariateVectorFunction,OptimizationData[])}
+     * instead.
      */
-    protected PointVectorValuePair optimizeInternal(final int maxEval, final MultivariateVectorFunction f,
+    @Deprecated
+    protected PointVectorValuePair optimizeInternal(final int maxEval, final FUNC f,
                                                     final double[] t, final double[] w,
                                                     final double[] startPoint) {
         // Checks.
@@ -147,28 +194,122 @@ public abstract class BaseAbstractMultivariateVectorOptimizer<FUNC extends Multi
             throw new DimensionMismatchException(t.length, w.length);
         }
 
-        // Reset.
-        evaluations.setMaximalCount(maxEval);
-        evaluations.resetCount();
-
-        // Store optimization problem characteristics.
-        function = f;
-        target = t.clone();
-        weight = w.clone();
-        start = startPoint.clone();
-
-        // Perform computation.
-        return doOptimize();
-
+        return optimizeInternal(maxEval, f,
+                                new Target(t),
+                                new Weight(w),
+                                new InitialGuess(startPoint));
     }
 
     /**
+     * Optimize an objective function.
+     *
+     * @param maxEval Allowed number of evaluations of the objective function.
+     * @param f Objective function.
+     * @param optData Optimization data. The following data will be looked for:
+     * <ul>
+     *  <li>{@link Target}</li>
+     *  <li>{@link Weight}</li>
+     *  <li>{@link InitialGuess}</li>
+     * </ul>
+     * @return the point/value pair giving the optimal value of the objective
+     * function.
+     * @throws TooManyEvaluationsException if the maximal number of
+     * evaluations is exceeded.
+     * @throws DimensionMismatchException if the initial guess, target, and weight
+     * arguments have inconsistent dimensions.
+     *
+     * @since 3.1
+     */
+    protected PointVectorValuePair optimizeInternal(int maxEval,
+                                                    FUNC f,
+                                                    OptimizationData... optData)
+        throws TooManyEvaluationsException,
+               DimensionMismatchException {
+        // Set internal state.
+        evaluations.setMaximalCount(maxEval);
+        evaluations.resetCount();
+        function = f;
+        // Retrieve other settings.
+        parseOptimizationData(optData);
+        // Check input consistency.
+        checkParameters();
+        // Allow subclasses to reset their own internal state.
+        setUp();
+        // Perform computation.
+        return doOptimize();
+    }
+
+    /**
+     * Gets the initial values of the optimized parameters.
+     *
      * @return the initial guess.
      */
     public double[] getStartPoint() {
         return start.clone();
     }
 
+    /**
+     * Gets the weight matrix of the observations.
+     *
+     * @return the weight matrix.
+     * @since 3.1
+     */
+    public RealMatrix getWeight() {
+        return weightMatrix.copy();
+    }
+    /**
+     * Gets the observed values to be matched by the objective vector
+     * function.
+     *
+     * @return the target values.
+     * @since 3.1
+     */
+    public double[] getTarget() {
+        return target.clone();
+    }
+
+    /**
+     * Computes the residuals.
+     * The residual is the difference between the observed (target)
+     * values and the model (objective function) value, for the given
+     * parameters.
+     * There is one residual for each element of the vector-valued
+     * function.
+     *
+     * @param point Parameters of the model.
+     * @return the residuals.
+     * @throws DimensionMismatchException if {@code point} has a wrong
+     * length.
+     * @since 3.1
+     */
+    protected double[] computeResidual(double[] point) {
+        if (point.length != start.length) {
+            throw new DimensionMismatchException(point.length,
+                                                 start.length);
+        }
+
+        final double[] objective = computeObjectiveValue(point);
+
+        final double[] residuals = new double[target.length];
+        for (int i = 0; i < target.length; i++) {
+            residuals[i] = target[i] - objective[i];
+        }
+
+        return residuals;
+    }
+
+
+    /**
+     * Gets the objective vector function.
+     * Note that this access bypasses the evaluation counter.
+     *
+     * @return the objective vector function.
+     * @since 3.1
+     */
+    protected FUNC getObjectiveFunction() {
+        return function;
+    }
+
     /**
      * Perform the bulk of the optimization algorithm.
      *
@@ -179,14 +320,80 @@ public abstract class BaseAbstractMultivariateVectorOptimizer<FUNC extends Multi
 
     /**
      * @return a reference to the {@link #target array}.
+     * @deprecated As of 3.1.
      */
+    @Deprecated
     protected double[] getTargetRef() {
         return target;
     }
     /**
      * @return a reference to the {@link #weight array}.
+     * @deprecated As of 3.1.
      */
+    @Deprecated
     protected double[] getWeightRef() {
         return weight;
     }
+
+    /**
+     * Method which a subclass <em>must</em> override whenever its internal
+     * state depend on the {@link OptimizationData input} parsed by this base
+     * class.
+     * It will be called after the parsing step performed in the
+     * {@link #optimize(int,MultivariateVectorFunction,OptimizationData[]) 
+     * optimize} method and just before {@link #doOptimize()}.
+     *
+     * @since 3.1
+     */
+    protected void setUp() {
+        // XXX Temporary code until the new internal data is used everywhere.
+        final int dim = target.length;
+        weight = new double[dim];
+        for (int i = 0; i < dim; i++) {
+            weight[i] = weightMatrix.getEntry(i, i);
+        }
+    }
+
+    /**
+     * Scans the list of (required and optional) optimization data that
+     * characterize the problem.
+     *
+     * @param optData Optimization data. The following data will be looked for:
+     * <ul>
+     *  <li>{@link Target}</li>
+     *  <li>{@link Weight}</li>
+     *  <li>{@link InitialGuess}</li>
+     * </ul>
+     */
+    private void parseOptimizationData(OptimizationData... optData) {
+        // The existing values (as set by the previous call) are reused if
+        // not provided in the argument list.
+        for (OptimizationData data : optData) {
+            if (data instanceof Target) {
+                target = ((Target) data).getTarget();
+                continue;
+            }
+            if (data instanceof Weight) {
+                weightMatrix = ((Weight) data).getWeight();
+                continue;
+            }
+            if (data instanceof InitialGuess) {
+                start = ((InitialGuess) data).getInitialGuess();
+                continue;
+            }
+        }
+    }
+
+    /**
+     * Check parameters consistency.
+     *
+     * @throws DimensionMismatchException if {@link #target} and
+     * {@link #weightMatrix} have inconsistent dimensions.
+     */
+    private void checkParameters() {
+        if (target.length != weightMatrix.getColumnDimension()) {
+            throw new DimensionMismatchException(target.length,
+                                                 weightMatrix.getColumnDimension());
+        }
+    }
 }
diff --git a/src/main/java/org/apache/commons/math3/optimization/general/AbstractLeastSquaresOptimizer.java b/src/main/java/org/apache/commons/math3/optimization/general/AbstractLeastSquaresOptimizer.java
index 3af449ce2..1288af11a 100644
--- a/src/main/java/org/apache/commons/math3/optimization/general/AbstractLeastSquaresOptimizer.java
+++ b/src/main/java/org/apache/commons/math3/optimization/general/AbstractLeastSquaresOptimizer.java
@@ -28,6 +28,10 @@ import org.apache.commons.math3.exception.util.LocalizedFormats;
 import org.apache.commons.math3.linear.DecompositionSolver;
 import org.apache.commons.math3.linear.MatrixUtils;
 import org.apache.commons.math3.linear.QRDecomposition;
+import org.apache.commons.math3.optimization.OptimizationData;
+import org.apache.commons.math3.optimization.InitialGuess;
+import org.apache.commons.math3.optimization.Target;
+import org.apache.commons.math3.optimization.Weight;
 import org.apache.commons.math3.optimization.ConvergenceChecker;
 import org.apache.commons.math3.optimization.DifferentiableMultivariateVectorOptimizer;
 import org.apache.commons.math3.optimization.PointVectorValuePair;
@@ -308,8 +312,10 @@ public abstract class AbstractLeastSquaresOptimizer
     }
 
     /** {@inheritDoc}
-     * @deprecated as of 3.1 replaced by {@link #optimize(int,
-     * MultivariateDifferentiableVectorFunction, double[], double[], double[])}
+     * @deprecated As of 3.1. Please use
+     * {@link BaseAbstractMultivariateVectorOptimizer#optimize(int,MultivariateVectorFunction,OptimizationData[])
+     * optimize(int,MultivariateDifferentiableVectorFunction,OptimizationData...)}
+     * instead.
      */
     @Override
     @Deprecated
@@ -317,8 +323,11 @@ public abstract class AbstractLeastSquaresOptimizer
                                          final DifferentiableMultivariateVectorFunction f,
                                          final double[] target, final double[] weights,
                                          final double[] startPoint) {
-        return optimize(maxEval, FunctionUtils.toMultivariateDifferentiableVectorFunction(f),
-                        target, weights, startPoint);
+        return optimizeInternal(maxEval,
+                                FunctionUtils.toMultivariateDifferentiableVectorFunction(f),
+                                new Target(target),
+                                new Weight(weights),
+                                new InitialGuess(startPoint));
     }
 
     /**
@@ -340,29 +349,78 @@ public abstract class AbstractLeastSquaresOptimizer
      * if the maximal number of evaluations is exceeded.
      * @throws org.apache.commons.math3.exception.NullArgumentException if
      * any argument is {@code null}.
+     * @deprecated As of 3.1. Please use
+     * {@link BaseAbstractMultivariateVectorOptimizer#optimize(int,MultivariateVectorFunction,OptimizationData[])
+     * optimize(int,MultivariateDifferentiableVectorFunction,OptimizationData...)}
+     * instead.
      */
+    @Deprecated
     public PointVectorValuePair optimize(final int maxEval,
                                          final MultivariateDifferentiableVectorFunction f,
                                          final double[] target, final double[] weights,
                                          final double[] startPoint) {
+        return optimizeInternal(maxEval, f,
+                                new Target(target),
+                                new Weight(weights),
+                                new InitialGuess(startPoint));
+    }
+
+    /**
+     * Optimize an objective function.
+     * Optimization is considered to be a weighted least-squares minimization.
+     * The cost function to be minimized is
+     * <code>&sum;weight<sub>i</sub>(objective<sub>i</sub> - target<sub>i</sub>)<sup>2</sup></code>
+     *
+     * @param maxEval Allowed number of evaluations of the objective function.
+     * @param f Objective function.
+     * @param optData Optimization data. The following data will be looked for:
+     * <ul>
+     *  <li>{@link Target}</li>
+     *  <li>{@link Weight}</li>
+     *  <li>{@link InitialGuess}</li>
+     * </ul>
+     * @return the point/value pair giving the optimal value of the objective
+     * function.
+     * @throws TooManyEvaluationsException if the maximal number of
+     * evaluations is exceeded.
+     * @throws DimensionMismatchException if the target, and weight arguments
+     * have inconsistent dimensions.
+     * @see BaseAbstractMultivariateVectorOptimizer#optimizeInternal(int,MultivariateVectorFunction,OptimizationData[])
+     *
+     * @since 3.1
+     */
+    protected PointVectorValuePair optimizeInternal(final int maxEval,
+                                                    final MultivariateDifferentiableVectorFunction f,
+                                                    OptimizationData... optData) {
+        // XXX Conversion will be removed when the generic argument of the
+        // base class becomes "MultivariateDifferentiableVectorFunction".
+        return super.optimizeInternal(maxEval, FunctionUtils.toDifferentiableMultivariateVectorFunction(f), optData);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    protected void setUp() {
+        super.setUp();
 
         // Reset counter.
         jacobianEvaluations = 0;
 
         // Store least squares problem characteristics.
-        jF = f;
+        // XXX The conversion won't be necessary when the generic argument of
+        // the base class becomes "MultivariateDifferentiableVectorFunction".
+        // XXX "jF" is not strictly necessary anymore but is currently more
+        // efficient than converting the value returned from "getObjectiveFunction()"
+        // every time it is used.
+        jF = FunctionUtils.toMultivariateDifferentiableVectorFunction((DifferentiableMultivariateVectorFunction) getObjectiveFunction());
 
         // Arrays shared with the other private methods.
-        point = startPoint.clone();
-        rows = target.length;
+        point = getStartPoint();
+        rows = getTarget().length;
         cols = point.length;
 
         weightedResidualJacobian = new double[rows][cols];
         this.weightedResiduals = new double[rows];
 
         cost = Double.POSITIVE_INFINITY;
-
-        return optimizeInternal(maxEval, f, target, weights, startPoint);
     }
-
 }