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<?php |
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/** |
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* Copyright (C) 2023 Graham Breach |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>. |
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*/ |
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/** |
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* For more information, please contact <graham@goat1000.com> |
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*/ |
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|
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namespace Goat1000\SVGGraph; |
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|
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/** |
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* Class for algebraic functions |
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*/ |
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class Algebraic { |
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|
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private $type = 'straight'; |
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private $coeffs = [0, 1]; |
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|
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public function __construct($type) |
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{ |
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$this->type = $type; |
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} |
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|
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/** |
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* Sets the coefficients in order, lowest power first |
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*/ |
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public function setCoefficients(array $coefficients) |
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{ |
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$this->coeffs = $coefficients; |
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} |
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|
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/** |
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* Returns the y value for a + bx + cx^2 ... |
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*/ |
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public function __invoke($x) |
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{ |
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$val = 0; |
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foreach($this->coeffs as $p => $c) { |
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switch($p) { |
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case 0: $val = bcadd($val, $c); |
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break; |
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case 1: $val = bcadd($val, bcmul($c, $x)); |
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break; |
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default: |
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$val = bcadd($val, bcmul($c, bcpow($x, $p))); |
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break; |
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} |
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} |
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return $val; |
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} |
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|
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/** |
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* Creates a row of the vandermonde matrix |
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*/ |
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public function vandermonde($x) |
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{ |
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$t = $this->type; |
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return $this->{$t}($x); |
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} |
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|
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private function straight($x) |
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{ |
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return [$x]; |
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} |
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|
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private function quadratic($x) |
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{ |
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return [$x, bcmul($x, $x)]; |
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} |
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|
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private function cubic($x) |
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{ |
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$res = [$x, bcmul($x, $x)]; |
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$res[] = bcmul($res[1], $x); |
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return $res; |
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} |
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|
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private function quartic($x) |
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{ |
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$res = $this->cubic($x); |
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$res[] = bcmul($res[1], $res[1]); |
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return $res; |
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} |
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|
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private function quintic($x) |
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{ |
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$res = $this->cubic($x); |
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$res[] = bcmul($res[1], $res[1]); |
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$res[] = bcmul($res[1], $res[2]); |
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return $res; |
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} |
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} |
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|
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