package org.djunits.vecmat.dn;
   
   import java.lang.reflect.Array;
   import java.util.Arrays;
   import java.util.Iterator;
   import java.util.List;
   import java.util.Objects;
   
   import org.djunits.quantity.SIQuantity;
  import org.djunits.quantity.def.Quantity;
  import org.djunits.unit.UnitInterface;
  import org.djunits.unit.si.SIUnit;
  import org.djunits.util.ArrayMath;
  import org.djunits.vecmat.def.Vector;
  import org.djunits.vecmat.storage.DataGridSi;
  import org.djunits.vecmat.storage.DenseDoubleDataSi;
  import org.djutils.exceptions.Throw;
  
  /**
   * VectorN.java.
   * <p>
   * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
   * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
   * @author Alexander Verbraeck
   * @param <Q> the quantity type
   * @param <V> the vector type (Row or Col)
   * @param <SI> the vector type with generics &lt;SIQuantity, SIUnit&lt;
   * @param <H> the generic vector type with generics &lt;?, ?&lt; for Hadamard operations
   * @param <VT> the type of the transposed version of the vector
   */
  public abstract class VectorN<Q extends Quantity<Q>, V extends VectorN<Q, V, SI, H, VT>,
          SI extends VectorN<SIQuantity, SI, ?, ?, ?>, H extends VectorN<?, ?, ?, ?, ?>, VT extends VectorN<Q, VT, ?, ?, V>>
          extends Vector<Q, V, SI, H, VT>
  {
      /** */
      private static final long serialVersionUID = 600L;
  
      /** The data of the matrix, in SI unit. */
      @SuppressWarnings("checkstyle:visibilitymodifier")
      protected final DataGridSi<?> dataSi;
  
      /**
       * Create a new VectorN with a unit, based on a DataGridSi storage object that contains SI data.
       * @param dataSi the data of the vector, in SI unit.
       * @param displayUnit the display unit to use
       * @throws IllegalArgumentException when the number of rows or columns does not have a positive value
       */
      protected VectorN(final DataGridSi<?> dataSi, final UnitInterface<Q> displayUnit)
      {
          super(displayUnit);
          Throw.whenNull(dataSi, "dataSi");
          this.dataSi = dataSi;
      }
  
      @Override
      public Iterator<Q> iterator()
      {
          final double[] si = this.dataSi.unsafeSiArray();
          final UnitInterface<Q> frozenDisplayUnit = getDisplayUnit(); // capture once
          return Arrays.stream(si).mapToObj(v -> frozenDisplayUnit.ofSi(v, frozenDisplayUnit)).iterator();
      }
  
      @Override
      public Q[] getScalarArray()
      {
          final double[] siArray = this.dataSi.unsafeSiArray();
          final UnitInterface<Q> frozenDisplayUnit = getDisplayUnit(); // capture once
          final Q first = frozenDisplayUnit.ofSi(siArray[0], frozenDisplayUnit);
          final Class<?> qClass = first.getClass();
          @SuppressWarnings("unchecked")
          final Q[] out = (Q[]) Array.newInstance(qClass, siArray.length);
          out[0] = first;
          for (int i = 1; i < siArray.length; i++)
          {
              out[i] = frozenDisplayUnit.ofSi(siArray[i], frozenDisplayUnit);
          }
          return out;
      }
  
      @Override
      public Q normL1()
      {
          double n = 0.0;
          for (var d : unsafeSiArray())
          {
              n += Math.abs(d);
          }
          return getDisplayUnit().ofSi(n, getDisplayUnit());
      }
  
      @Override
      public Q normL2()
      {
          double n = 0.0;
          for (var d : unsafeSiArray())
          {
              n += d * d;
          }
         return getDisplayUnit().ofSi(Math.sqrt(n), getDisplayUnit());
     }
 
     @Override
     public Q normLp(final int p)
     {
         double n = 0.0;
         for (var d : unsafeSiArray())
         {
             n += Math.pow(Math.abs(d), p);
         }
         return getDisplayUnit().ofSi(Math.pow(n, 1.0 / p), getDisplayUnit());
     }
 
     @Override
     public Q normLinf()
     {
         double max = Double.NEGATIVE_INFINITY;
         for (var d : unsafeSiArray())
         {
             max = Math.max(Math.abs(d), max);
         }
         return getDisplayUnit().ofSi(max, getDisplayUnit());
     }
 
     @Override
     public int rows()
     {
         return this.dataSi.rows();
     }
 
     @Override
     public int cols()
     {
         return this.dataSi.cols();
     }
 
     @Override
     public double[] getSiArray()
     {
         return this.dataSi.getSiArray();
     }
 
     @Override
     public double[] unsafeSiArray()
     {
         return this.dataSi.unsafeSiArray();
     }
 
     @Override
     public int nonZeroCount()
     {
         return this.dataSi.nonZeroCount();
     }
 
     @Override
     public int hashCode()
     {
         return Objects.hash(this.dataSi, rows(), cols());
     }
 
     @SuppressWarnings("checkstyle:needbraces")
     @Override
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         VectorN<?, ?, ?, ?, ?> other = (VectorN<?, ?, ?, ?, ?>) obj;
         return Objects.equals(this.dataSi, other.dataSi) && rows() == other.rows() && cols() == other.cols();
     }
 
     /**
      * VectorN.Col implements a column vector with real-valued entries. The vector is immutable, except for the display unit,
      * which can be changed.
      * <p>
      * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
      * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
      * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
      * @author Alexander Verbraeck
      * @param <Q> the quantity type
      */
     public static class Col<Q extends Quantity<Q>> extends
             VectorN<Q, Col<Q>, VectorN.Col<SIQuantity>, VectorN.Col<?>, VectorN.Row<Q>> implements Vector.Col<VectorN.Col<Q>, Q>
     {
         /** */
         private static final long serialVersionUID = 600L;
 
         /**
          * Create a new column VectorN with a unit, based on a DataGridSi storage object that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @throws IllegalArgumentException when the number of rows or columns does not have a positive value or when the vector
          *             is initialized with more than one row
          */
         public Col(final DataGridSi<?> dataSi, final UnitInterface<Q> displayUnit)
         {
             super(dataSi, displayUnit);
             Throw.when(dataSi.cols() != 1, IllegalArgumentException.class,
                     "Column vector initialized with more than one column");
         }
 
         @Override
         public VectorN.Col<Q> instantiateSi(final double[] data, final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Col<Q>(this.dataSi.instantiateNew(data), displayUnit);
         }
 
         @Override
         public Col<SIQuantity> instantiateSi(final double[] siNew, final SIUnit siUnit)
         {
             return new VectorN.Col<SIQuantity>(this.dataSi.instantiateNew(siNew), siUnit);
         }
 
         @Override
         public boolean isColumnVector()
         {
             return true;
         }
 
         @Override
         public int size()
         {
             return this.dataSi.rows();
         }
 
         @Override
         public double si(final int index) throws IndexOutOfBoundsException
         {
             return this.dataSi.get(index, 0);
         }
 
         @Override
         public VectorN.Row<Q> transpose()
         {
             var newSi = this.dataSi.instantiateNew(unsafeSiArray(), cols(), rows());
             return new VectorN.Row<Q>(newSi, getDisplayUnit());
         }
 
         @Override
         public VectorN.Col<SIQuantity> invertEntries()
         {
             SIUnit siUnit = getDisplayUnit().siUnit().invert();
             return new VectorN.Col<SIQuantity>(this.dataSi.instantiateNew(ArrayMath.reciprocal(unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Col<SIQuantity> multiplyEntries(final VectorN.Col<?> other)
         {
             SIUnit siUnit = SIUnit.add(getDisplayUnit().siUnit(), other.getDisplayUnit().siUnit());
             return new VectorN.Col<SIQuantity>(
                     this.dataSi.instantiateNew(ArrayMath.multiply(unsafeSiArray(), other.unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Col<SIQuantity> divideEntries(final VectorN.Col<?> other)
         {
             SIUnit siUnit = SIUnit.subtract(getDisplayUnit().siUnit(), other.getDisplayUnit().siUnit());
             return new VectorN.Col<SIQuantity>(
                     this.dataSi.instantiateNew(ArrayMath.divide(unsafeSiArray(), other.unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Col<SIQuantity> multiplyEntries(final Quantity<?> quantity)
         {
             SIUnit siUnit = SIUnit.add(getDisplayUnit().siUnit(), quantity.getDisplayUnit().siUnit());
             return new VectorN.Col<SIQuantity>(this.dataSi.instantiateNew(ArrayMath.scaleBy(unsafeSiArray(), quantity.si())),
                     siUnit);
         }
 
         // ------------------------------------------ OF METHODS ------------------------------------------
 
         /**
          * Create a new column VectorN with a unit, based on a double[] array that contains data in the given unit.
          * @param dataInUnit the data of the vector, in the given unit.
          * @param unit the unit of the data
          * @return a new column VectorN with a unit, based on a double[] array expressed in the given unit
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Col<Q> of(final double[] dataInUnit, final UnitInterface<Q> unit)
         {
             double[] dataSi = new double[dataInUnit.length];
             for (int i = 0; i < dataInUnit.length; i++)
             {
                 dataSi[i] = unit.toBaseValue(dataInUnit[i]);
             }
             return ofSi(dataSi, unit);
         }
 
         /**
          * Create a new column VectorN with a unit, based on a double[] array that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @return a new column VectorN with a unit, based on a double[] array that contains SI data
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Col<Q> ofSi(final double[] dataSi, final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Col<Q>(new DenseDoubleDataSi(dataSi.clone(), dataSi.length, 1), displayUnit);
         }
 
         /**
          * Create a new column VectorN with a unit, based on a quantity array that contains data. The display unit will be taken
          * from the first quantity in the array.
          * @param data the data of the vector, in the given unit.
          * @return a new column VectorN with a display unit, based on a quantity array
          * @throws IllegalArgumentException when data array length is less than 1
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Col<Q> of(final Q[] data)
         {
             Throw.when(data.length < 1, IllegalArgumentException.class, "data array length < 1");
             double[] dataSi = new double[data.length];
             for (int i = 0; i < data.length; i++)
             {
                 dataSi[i] = data[i].si();
             }
             return ofSi(dataSi, data[0].getDisplayUnit());
         }
 
         /**
          * Create a new column VectorN with a unit, based on a DataGridSi storage object that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @throws IllegalArgumentException when the number of rows or columns does not have a positive value or when the vector
          *             is initialized with more than one row
          * @return a new column VectorN with a unit, based on a DataGridSi storage object that contains SI data
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Col<Q> ofSi(final DataGridSi<?> dataSi,
                 final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Col<Q>(dataSi, displayUnit);
         }
 
         /**
          * Create a new column VectorN with a unit, based on a quantity list that contains data. The display unit will be taken
          * from the first quantity in the list.
          * @param data the data of the vector, in the given unit.
          * @return a new column VectorN with a display unit, based on a quantity list
          * @throws IllegalArgumentException when data size is less than 1
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Col<Q> of(final List<Q> data)
         {
             Throw.when(data.size() < 1, IllegalArgumentException.class, "data.size < 1");
             double[] dataSi = new double[data.size()];
             for (int i = 0; i < data.size(); i++)
             {
                 dataSi[i] = data.get(i).si();
             }
             return ofSi(dataSi, data.get(0).getDisplayUnit());
         }
 
         // ------------------------------------------ AS METHODS ------------------------------------------
 
         /**
          * Return the vector 'as' a vector with a known quantity, using a unit to express the result in. Throw a Runtime
          * exception when the SI units of this vector and the target vector do not match. The dataSi object containing the
          * vector values is NOT copied.
          * @param targetUnit the unit to convert the vector to
          * @return a quantity typed in the target vector class
          * @throws IllegalArgumentException when the units do not match
          * @param <TQ> target quantity type
          */
         public <TQ extends Quantity<TQ>> VectorN.Col<TQ> as(final UnitInterface<TQ> targetUnit) throws IllegalArgumentException
         {
             Throw.when(!getDisplayUnit().siUnit().equals(targetUnit.siUnit()), IllegalArgumentException.class,
                     "Quantity.as(%s) called, but units do not match: %s <> %s", targetUnit,
                     getDisplayUnit().siUnit().getDisplayAbbreviation(), targetUnit.siUnit().getDisplayAbbreviation());
             return new VectorN.Col<TQ>(this.dataSi, targetUnit);
         }
 
     }
 
     /**
      * VectorN.Row implements a row vector with real-valued entries. The vector is immutable, except for the display unit, which
      * can be changed.
      * <p>
      * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
      * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
      * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
      * @author Alexander Verbraeck
      * @param <Q> the quantity type
      */
     public static class Row<Q extends Quantity<Q>> extends
             VectorN<Q, Row<Q>, VectorN.Row<SIQuantity>, VectorN.Row<?>, VectorN.Col<Q>> implements Vector.Row<VectorN.Row<Q>, Q>
     {
         /** */
         private static final long serialVersionUID = 600L;
 
         /**
          * Create a new row VectorN with a unit, based on a DataGridSi storage object that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @throws IllegalArgumentException when the number of rows or columns does not have a positive value or when the vector
          *             is initialized with more than one row
          */
         public Row(final DataGridSi<?> dataSi, final UnitInterface<Q> displayUnit)
         {
             super(dataSi, displayUnit);
             Throw.when(dataSi.rows() != 1, IllegalArgumentException.class, "Row vector initialized with more than one row");
         }
 
         @Override
         public boolean isColumnVector()
         {
             return false;
         }
 
         @Override
         public VectorN.Row<Q> instantiateSi(final double[] data, final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Row<>(this.dataSi.instantiateNew(data), displayUnit);
         }
 
         @Override
         public VectorN.Row<SIQuantity> instantiateSi(final double[] siNew, final SIUnit siUnit)
         {
             return new VectorN.Row<SIQuantity>(this.dataSi.instantiateNew(siNew), siUnit);
         }
 
         @Override
         public int size()
         {
             return this.dataSi.cols();
         }
 
         @Override
         public double si(final int index) throws IndexOutOfBoundsException
         {
             return this.dataSi.get(0, index);
         }
 
         @Override
         public VectorN.Col<Q> transpose()
         {
             var newSi = this.dataSi.instantiateNew(unsafeSiArray(), cols(), rows());
             return new VectorN.Col<Q>(newSi, getDisplayUnit());
         }
 
         @Override
         public VectorN.Row<SIQuantity> invertEntries()
         {
             SIUnit siUnit = getDisplayUnit().siUnit().invert();
             return new VectorN.Row<SIQuantity>(this.dataSi.instantiateNew(ArrayMath.reciprocal(unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Row<SIQuantity> multiplyEntries(final VectorN.Row<?> other)
         {
             SIUnit siUnit = SIUnit.add(getDisplayUnit().siUnit(), other.getDisplayUnit().siUnit());
             return new VectorN.Row<SIQuantity>(
                     this.dataSi.instantiateNew(ArrayMath.multiply(unsafeSiArray(), other.unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Row<SIQuantity> divideEntries(final VectorN.Row<?> other)
         {
             SIUnit siUnit = SIUnit.subtract(getDisplayUnit().siUnit(), other.getDisplayUnit().siUnit());
             return new VectorN.Row<SIQuantity>(
                     this.dataSi.instantiateNew(ArrayMath.divide(unsafeSiArray(), other.unsafeSiArray())), siUnit);
         }
 
         @Override
         public VectorN.Row<SIQuantity> multiplyEntries(final Quantity<?> quantity)
         {
             SIUnit siUnit = SIUnit.add(getDisplayUnit().siUnit(), quantity.getDisplayUnit().siUnit());
             return new VectorN.Row<SIQuantity>(this.dataSi.instantiateNew(ArrayMath.scaleBy(unsafeSiArray(), quantity.si())),
                     siUnit);
         }
 
         // ------------------------------------------ OF METHODS ------------------------------------------
 
         /**
          * Create a new row VectorN with a unit, based on a double[] array that contains data in the given unit.
          * @param dataInUnit the data of the vector, in the given unit.
          * @param unit the unit of the data
          * @return a new row VectorN with a unit, based on a double[] array expressed in the given unit
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Row<Q> of(final double[] dataInUnit, final UnitInterface<Q> unit)
         {
             double[] dataSi = new double[dataInUnit.length];
             for (int i = 0; i < dataInUnit.length; i++)
             {
                 dataSi[i] = unit.toBaseValue(dataInUnit[i]);
             }
             return ofSi(dataSi, unit);
         }
 
         /**
          * Create a new row VectorN with a unit, based on a double[] array that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @return a new row VectorN with a unit, based on a double[] array that contains SI data
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Row<Q> ofSi(final double[] dataSi, final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Row<Q>(new DenseDoubleDataSi(dataSi.clone(), 1, dataSi.length), displayUnit);
         }
 
         /**
          * Create a new row VectorN with a unit, based on a quantity array that contains data. The display unit will be taken
          * from the first quantity in the array.
          * @param data the data of the vector, in the given unit.
          * @return a new row VectorN with a display unit, based on a quantity array
          * @throws IllegalArgumentException when data array length is less than 1
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Row<Q> of(final Q[] data)
         {
             Throw.when(data.length < 1, IllegalArgumentException.class, "data array length < 1");
             double[] dataSi = new double[data.length];
             for (int i = 0; i < data.length; i++)
             {
                 dataSi[i] = data[i].si();
             }
             return ofSi(dataSi, data[0].getDisplayUnit());
         }
 
         /**
          * Create a new row VectorN with a unit, based on a DataGridSi storage object that contains SI data.
          * @param dataSi the data of the vector, in SI unit.
          * @param displayUnit the display unit to use
          * @throws IllegalArgumentException when the number of rows or rows does not have a positive value or when the vector is
          *             initialized with more than one row
          * @return a new row VectorN with a unit, based on a DataGridSi storage object that contains SI data
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Row<Q> ofSi(final DataGridSi<?> dataSi,
                 final UnitInterface<Q> displayUnit)
         {
             return new VectorN.Row<Q>(dataSi, displayUnit);
         }
 
         /**
          * Create a new row VectorN with a unit, based on a quantity list that contains data. The display unit will be taken
          * from the first quantity in the list.
          * @param data the data of the vector, in the given unit.
          * @return a new row VectorN with a display unit, based on a quantity list
          * @throws IllegalArgumentException when data size is less than 1
          * @param <Q> the quantity type
          */
         public static <Q extends Quantity<Q>> VectorN.Row<Q> of(final List<Q> data)
         {
             Throw.when(data.size() < 1, IllegalArgumentException.class, "data.size < 1");
             double[] dataSi = new double[data.size()];
             for (int i = 0; i < data.size(); i++)
             {
                 dataSi[i] = data.get(i).si();
             }
             return ofSi(dataSi, data.get(0).getDisplayUnit());
         }
 
         // ------------------------------------------ AS METHODS ------------------------------------------
 
         /**
          * Return the vector 'as' a vector with a known quantity, using a unit to express the result in. Throw a Runtime
          * exception when the SI units of this vector and the target vector do not match. The dataSi object containing the
          * vector values is NOT copied.
          * @param targetUnit the unit to convert the vector to
          * @return a quantity typed in the target vector class
          * @throws IllegalArgumentException when the units do not match
          * @param <TQ> target quantity type
          */
         public <TQ extends Quantity<TQ>> VectorN.Row<TQ> as(final UnitInterface<TQ> targetUnit) throws IllegalArgumentException
         {
             Throw.when(!getDisplayUnit().siUnit().equals(targetUnit.siUnit()), IllegalArgumentException.class,
                     "Quantity.as(%s) called, but units do not match: %s <> %s", targetUnit,
                     getDisplayUnit().siUnit().getDisplayAbbreviation(), targetUnit.siUnit().getDisplayAbbreviation());
             return new VectorN.Row<TQ>(this.dataSi, targetUnit);
         }
 
     }
 
 }