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/** @file
* @brief Unit tests for Polynomial and related functions.
* Uses the Google Testing Framework
*//*
* Authors:
* Krzysztof Kosiński <tweenk.pl@gmail.com>
*
* Copyright 2015-2019 Authors
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (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.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*/
#include "testing.h"
#include <iostream>
#include <glib.h>
#include <2geom/polynomial.h>
using namespace Geom;
TEST(PolynomialTest, SolveQuadratic) {
for (unsigned i = 0; i < 1000; ++i) {
Coord x1 = g_random_double_range(-100, 100);
Coord x2 = g_random_double_range(-100, 100);
Coord a = g_random_double_range(-10, 10);
Coord b = -a * (x1 + x2);
Coord c = a * x1 * x2;
std::vector<Coord> result = solve_quadratic(a, b, c);
EXPECT_EQ(result.size(), 2u);
if (x1 < x2) {
EXPECT_FLOAT_EQ(result[0], x1);
EXPECT_FLOAT_EQ(result[1], x2);
} else {
EXPECT_FLOAT_EQ(result[0], x2);
EXPECT_FLOAT_EQ(result[1], x1);
}
}
}
TEST(PolynomialTest, SolvePathologicalQuadratic) {
std::vector<Coord> r;
r = solve_quadratic(1, -1e9, 1);
ASSERT_EQ(r.size(), 2u);
EXPECT_FLOAT_EQ(r[0], 1e-9);
EXPECT_FLOAT_EQ(r[1], 1e9);
r = solve_quadratic(1, -4, 3.999999);
ASSERT_EQ(r.size(), 2u);
EXPECT_FLOAT_EQ(r[0], 1.999);
EXPECT_FLOAT_EQ(r[1], 2.001);
r = solve_quadratic(1, 0, -4);
ASSERT_EQ(r.size(), 2u);
EXPECT_FLOAT_EQ(r[0], -2);
EXPECT_FLOAT_EQ(r[1], 2);
r = solve_quadratic(1, 0, -16);
ASSERT_EQ(r.size(), 2u);
EXPECT_FLOAT_EQ(r[0], -4);
EXPECT_FLOAT_EQ(r[1], 4);
r = solve_quadratic(1, 0, -100);
ASSERT_EQ(r.size(), 2u);
EXPECT_FLOAT_EQ(r[0], -10);
EXPECT_FLOAT_EQ(r[1], 10);
}
TEST(PolynomialTest, SolveCubic) {
for (unsigned i = 0; i < 1000; ++i) {
Coord x1 = g_random_double_range(-100, 100);
Coord x2 = g_random_double_range(-100, 100);
Coord x3 = g_random_double_range(-100, 100);
Coord a = g_random_double_range(-10, 10);
Coord b = -a * (x1 + x2 + x3);
Coord c = a * (x1*x2 + x2*x3 + x1*x3);
Coord d = -a * x1 * x2 * x3;
std::vector<Coord> result = solve_cubic(a, b, c, d);
std::vector<Coord> x(3); x[0] = x1; x[1] = x2; x[2] = x3;
std::sort(x.begin(), x.end());
ASSERT_EQ(result.size(), 3u);
EXPECT_FLOAT_EQ(result[0], x[0]);
EXPECT_FLOAT_EQ(result[1], x[1]);
EXPECT_FLOAT_EQ(result[2], x[2]);
}
// corner cases
// (x^2 + 7)(x - 2)
std::vector<Coord> r1 = solve_cubic(1, -2, 7, -14);
EXPECT_EQ(r1.size(), 1u);
EXPECT_FLOAT_EQ(r1[0], 2);
// (x + 1)^2 (x-2)
std::vector<Coord> r2 = solve_cubic(1, 0, -3, -2);
ASSERT_EQ(r2.size(), 3u);
EXPECT_FLOAT_EQ(r2[0], -1);
EXPECT_FLOAT_EQ(r2[1], -1);
EXPECT_FLOAT_EQ(r2[2], 2);
}
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