/** * @covers Marando\Meeus\Nutation\Nutation::find * @see p.148, ex. 22.a */ public function testFind() { $n = Nutation::find(AstroDate::parse('1987-Apr-10')); $this->assertEquals(-3.788 / 3600, $n->long->deg, 'Δψ', 1.0E-6); $this->assertEquals(+9.443 / 3600, $n->obli->deg, 'Δε', 1.0E-6); }
/** * Finds the true obliquity of the ecliptic (ε = ε0 + Δε) for a given date. * * @param AstroDate $date Date to calculate the ε for * @return Angle True obliquity of the ecliptic (ε) */ public static function trueObliquity(AstroDate $date) { $n = Nutation::find($date); $ε0 = static::meanObliquity($date); // ε = ε0 + Δε return $ε = $ε0->add($n->obli); }