/*
 * Copyright (c) 2009-2020, Peter Abeles. All Rights Reserved.
 *
 * This file is part of Efficient Java Matrix Library (EJML).
 *
 * Licensed 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.ejml.generic;

import org.ejml.data.DMatrix;

import java.util.Random;

/**
 * @author Peter Abeles
 */
public class GenericMatrixOps_F64 {

//    public static DenseD2Matrix64F convertToD2( DMatrixRMaj orig ) {
//        DenseD2Matrix64F ret = new DenseD2Matrix64F(orig.getNumRows(),orig.getNumCols());
//
//        copy(orig,ret);
//
//        return ret;
//    }

    public static boolean isEquivalent( DMatrix a, DMatrix b, double tol ) {
        if (a.getNumRows() != b.getNumRows() || a.getNumCols() != b.getNumCols())
            return false;

        for (int i = 0; i < a.getNumRows(); i++) {
            for (int j = 0; j < a.getNumCols(); j++) {
                double diff = Math.abs(a.get(i, j) - b.get(i, j));

                if (diff > tol)
                    return false;
            }
        }

        return true;
    }

    /**
     * Returns true if the provided matrix is has a value of 1 along the diagonal
     * elements and zero along all the other elements.
     *
     * @param a Matrix being inspected.
     * @param tol How close to zero or one each element needs to be.
     * @return If it is within tolerance to an identity matrix.
     */
    public static boolean isIdentity( DMatrix a, double tol ) {
        for (int i = 0; i < a.getNumRows(); i++) {
            for (int j = 0; j < a.getNumCols(); j++) {
                if (i == j) {
                    if (Math.abs(a.get(i, j) - 1.0) > tol)
                        return false;
                } else {
                    if (Math.abs(a.get(i, j)) > tol)
                        return false;
                }
            }
        }
        return true;
    }

    public static boolean isEquivalentTriangle( boolean upper, DMatrix a, DMatrix b, double tol ) {
        if (a.getNumRows() != b.getNumRows() || a.getNumCols() != b.getNumCols())
            return false;

        if (upper) {
            for (int i = 0; i < a.getNumRows(); i++) {
                for (int j = i; j < a.getNumCols(); j++) {
                    double diff = Math.abs(a.get(i, j) - b.get(i, j));

                    if (diff > tol)
                        return false;
                }
            }
        } else {
            for (int j = 0; j < a.getNumCols(); j++) {
                for (int i = j; i < a.getNumRows(); i++) {
                    double diff = Math.abs(a.get(i, j) - b.get(i, j));

                    if (diff > tol)
                        return false;
                }
            }
        }

        return true;
    }

    public static void copy( DMatrix from, DMatrix to ) {
        int numCols = from.getNumCols();
        int numRows = from.getNumRows();

        for (int i = 0; i < numRows; i++) {
            for (int j = 0; j < numCols; j++) {
                to.set(i, j, from.get(i, j));
            }
        }
    }

    public static void setRandom( DMatrix a, double min, double max, Random rand ) {
        for (int i = 0; i < a.getNumRows(); i++) {
            for (int j = 0; j < a.getNumCols(); j++) {
                double val = rand.nextDouble()*(max - min) + min;
                a.set(i, j, val);
            }
        }
    }
}
