SingularValueDecomposition.php 18.2 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528
<?php
/**
 *    @package JAMA
 *
 *    For an m-by-n matrix A with m >= n, the singular value decomposition is
 *    an m-by-n orthogonal matrix U, an n-by-n diagonal matrix S, and
 *    an n-by-n orthogonal matrix V so that A = U*S*V'.
 *
 *    The singular values, sigma[$k] = S[$k][$k], are ordered so that
 *    sigma[0] >= sigma[1] >= ... >= sigma[n-1].
 *
 *    The singular value decompostion always exists, so the constructor will
 *    never fail.  The matrix condition number and the effective numerical
 *    rank can be computed from this decomposition.
 *
 *    @author  Paul Meagher
 *    @license PHP v3.0
 *    @version 1.1
 */
class SingularValueDecomposition
{
    /**
     *    Internal storage of U.
     *    @var array
     */
    private $U = array();

    /**
     *    Internal storage of V.
     *    @var array
     */
    private $V = array();

    /**
     *    Internal storage of singular values.
     *    @var array
     */
    private $s = array();

    /**
     *    Row dimension.
     *    @var int
     */
    private $m;

    /**
     *    Column dimension.
     *    @var int
     */
    private $n;

    /**
     *    Construct the singular value decomposition
     *
     *    Derived from LINPACK code.
     *
     *    @param $A Rectangular matrix
     *    @return Structure to access U, S and V.
     */
    public function __construct($Arg)
    {
        // Initialize.
        $A = $Arg->getArrayCopy();
        $this->m = $Arg->getRowDimension();
        $this->n = $Arg->getColumnDimension();
        $nu      = min($this->m, $this->n);
        $e       = array();
        $work    = array();
        $wantu   = true;
        $wantv   = true;
        $nct = min($this->m - 1, $this->n);
        $nrt = max(0, min($this->n - 2, $this->m));

        // Reduce A to bidiagonal form, storing the diagonal elements
        // in s and the super-diagonal elements in e.
        for ($k = 0; $k < max($nct, $nrt); ++$k) {
            if ($k < $nct) {
                // Compute the transformation for the k-th column and
                // place the k-th diagonal in s[$k].
                // Compute 2-norm of k-th column without under/overflow.
                $this->s[$k] = 0;
                for ($i = $k; $i < $this->m; ++$i) {
                    $this->s[$k] = hypo($this->s[$k], $A[$i][$k]);
                }
                if ($this->s[$k] != 0.0) {
                    if ($A[$k][$k] < 0.0) {
                        $this->s[$k] = -$this->s[$k];
                    }
                    for ($i = $k; $i < $this->m; ++$i) {
                        $A[$i][$k] /= $this->s[$k];
                    }
                    $A[$k][$k] += 1.0;
                }
                $this->s[$k] = -$this->s[$k];
            }

            for ($j = $k + 1; $j < $this->n; ++$j) {
                if (($k < $nct) & ($this->s[$k] != 0.0)) {
                    // Apply the transformation.
                    $t = 0;
                    for ($i = $k; $i < $this->m; ++$i) {
                        $t += $A[$i][$k] * $A[$i][$j];
                    }
                    $t = -$t / $A[$k][$k];
                    for ($i = $k; $i < $this->m; ++$i) {
                        $A[$i][$j] += $t * $A[$i][$k];
                    }
                    // Place the k-th row of A into e for the
                    // subsequent calculation of the row transformation.
                    $e[$j] = $A[$k][$j];
                }
            }

            if ($wantu and ($k < $nct)) {
                // Place the transformation in U for subsequent back
                // multiplication.
                for ($i = $k; $i < $this->m; ++$i) {
                    $this->U[$i][$k] = $A[$i][$k];
                }
            }

            if ($k < $nrt) {
                // Compute the k-th row transformation and place the
                // k-th super-diagonal in e[$k].
                // Compute 2-norm without under/overflow.
                $e[$k] = 0;
                for ($i = $k + 1; $i < $this->n; ++$i) {
                    $e[$k] = hypo($e[$k], $e[$i]);
                }
                if ($e[$k] != 0.0) {
                    if ($e[$k+1] < 0.0) {
                        $e[$k] = -$e[$k];
                    }
                    for ($i = $k + 1; $i < $this->n; ++$i) {
                        $e[$i] /= $e[$k];
                    }
                    $e[$k+1] += 1.0;
                }
                $e[$k] = -$e[$k];
                if (($k+1 < $this->m) and ($e[$k] != 0.0)) {
                    // Apply the transformation.
                    for ($i = $k+1; $i < $this->m; ++$i) {
                        $work[$i] = 0.0;
                    }
                    for ($j = $k+1; $j < $this->n; ++$j) {
                        for ($i = $k+1; $i < $this->m; ++$i) {
                            $work[$i] += $e[$j] * $A[$i][$j];
                        }
                    }
                    for ($j = $k + 1; $j < $this->n; ++$j) {
                        $t = -$e[$j] / $e[$k+1];
                        for ($i = $k + 1; $i < $this->m; ++$i) {
                            $A[$i][$j] += $t * $work[$i];
                        }
                    }
                }
                if ($wantv) {
                    // Place the transformation in V for subsequent
                    // back multiplication.
                    for ($i = $k + 1; $i < $this->n; ++$i) {
                        $this->V[$i][$k] = $e[$i];
                    }
                }
            }
        }

        // Set up the final bidiagonal matrix or order p.
        $p = min($this->n, $this->m + 1);
        if ($nct < $this->n) {
            $this->s[$nct] = $A[$nct][$nct];
        }
        if ($this->m < $p) {
            $this->s[$p-1] = 0.0;
        }
        if ($nrt + 1 < $p) {
            $e[$nrt] = $A[$nrt][$p-1];
        }
        $e[$p-1] = 0.0;
        // If required, generate U.
        if ($wantu) {
            for ($j = $nct; $j < $nu; ++$j) {
                for ($i = 0; $i < $this->m; ++$i) {
                    $this->U[$i][$j] = 0.0;
                }
                $this->U[$j][$j] = 1.0;
            }
            for ($k = $nct - 1; $k >= 0; --$k) {
                if ($this->s[$k] != 0.0) {
                    for ($j = $k + 1; $j < $nu; ++$j) {
                        $t = 0;
                        for ($i = $k; $i < $this->m; ++$i) {
                            $t += $this->U[$i][$k] * $this->U[$i][$j];
                        }
                        $t = -$t / $this->U[$k][$k];
                        for ($i = $k; $i < $this->m; ++$i) {
                            $this->U[$i][$j] += $t * $this->U[$i][$k];
                        }
                    }
                    for ($i = $k; $i < $this->m; ++$i) {
                        $this->U[$i][$k] = -$this->U[$i][$k];
                    }
                    $this->U[$k][$k] = 1.0 + $this->U[$k][$k];
                    for ($i = 0; $i < $k - 1; ++$i) {
                        $this->U[$i][$k] = 0.0;
                    }
                } else {
                    for ($i = 0; $i < $this->m; ++$i) {
                        $this->U[$i][$k] = 0.0;
                    }
                    $this->U[$k][$k] = 1.0;
                }
            }
        }

        // If required, generate V.
        if ($wantv) {
            for ($k = $this->n - 1; $k >= 0; --$k) {
                if (($k < $nrt) and ($e[$k] != 0.0)) {
                    for ($j = $k + 1; $j < $nu; ++$j) {
                        $t = 0;
                        for ($i = $k + 1; $i < $this->n; ++$i) {
                            $t += $this->V[$i][$k]* $this->V[$i][$j];
                        }
                        $t = -$t / $this->V[$k+1][$k];
                        for ($i = $k + 1; $i < $this->n; ++$i) {
                            $this->V[$i][$j] += $t * $this->V[$i][$k];
                        }
                    }
                }
                for ($i = 0; $i < $this->n; ++$i) {
                    $this->V[$i][$k] = 0.0;
                }
                $this->V[$k][$k] = 1.0;
            }
        }

        // Main iteration loop for the singular values.
        $pp   = $p - 1;
        $iter = 0;
        $eps  = pow(2.0, -52.0);

        while ($p > 0) {
            // Here is where a test for too many iterations would go.
            // This section of the program inspects for negligible
            // elements in the s and e arrays.  On completion the
            // variables kase and k are set as follows:
            // kase = 1  if s(p) and e[k-1] are negligible and k<p
            // kase = 2  if s(k) is negligible and k<p
            // kase = 3  if e[k-1] is negligible, k<p, and
            //           s(k), ..., s(p) are not negligible (qr step).
            // kase = 4  if e(p-1) is negligible (convergence).
            for ($k = $p - 2; $k >= -1; --$k) {
                if ($k == -1) {
                    break;
                }
                if (abs($e[$k]) <= $eps * (abs($this->s[$k]) + abs($this->s[$k+1]))) {
                    $e[$k] = 0.0;
                    break;
                }
            }
            if ($k == $p - 2) {
                $kase = 4;
            } else {
                for ($ks = $p - 1; $ks >= $k; --$ks) {
                    if ($ks == $k) {
                        break;
                    }
                    $t = ($ks != $p ? abs($e[$ks]) : 0.) + ($ks != $k + 1 ? abs($e[$ks-1]) : 0.);
                    if (abs($this->s[$ks]) <= $eps * $t) {
                        $this->s[$ks] = 0.0;
                        break;
                    }
                }
                if ($ks == $k) {
                    $kase = 3;
                } elseif ($ks == $p-1) {
                    $kase = 1;
                } else {
                    $kase = 2;
                    $k = $ks;
                }
            }
            ++$k;

            // Perform the task indicated by kase.
            switch ($kase) {
                // Deflate negligible s(p).
                case 1:
                    $f = $e[$p-2];
                    $e[$p-2] = 0.0;
                    for ($j = $p - 2; $j >= $k; --$j) {
                        $t  = hypo($this->s[$j], $f);
                        $cs = $this->s[$j] / $t;
                        $sn = $f / $t;
                        $this->s[$j] = $t;
                        if ($j != $k) {
                            $f = -$sn * $e[$j-1];
                            $e[$j-1] = $cs * $e[$j-1];
                        }
                        if ($wantv) {
                            for ($i = 0; $i < $this->n; ++$i) {
                                $t = $cs * $this->V[$i][$j] + $sn * $this->V[$i][$p-1];
                                $this->V[$i][$p-1] = -$sn * $this->V[$i][$j] + $cs * $this->V[$i][$p-1];
                                $this->V[$i][$j] = $t;
                            }
                        }
                    }
                    break;
                // Split at negligible s(k).
                case 2:
                    $f = $e[$k-1];
                    $e[$k-1] = 0.0;
                    for ($j = $k; $j < $p; ++$j) {
                        $t = hypo($this->s[$j], $f);
                        $cs = $this->s[$j] / $t;
                        $sn = $f / $t;
                        $this->s[$j] = $t;
                        $f = -$sn * $e[$j];
                        $e[$j] = $cs * $e[$j];
                        if ($wantu) {
                            for ($i = 0; $i < $this->m; ++$i) {
                                $t = $cs * $this->U[$i][$j] + $sn * $this->U[$i][$k-1];
                                $this->U[$i][$k-1] = -$sn * $this->U[$i][$j] + $cs * $this->U[$i][$k-1];
                                $this->U[$i][$j] = $t;
                            }
                        }
                    }
                    break;
                // Perform one qr step.
                case 3:
                    // Calculate the shift.
                    $scale = max(max(max(max(abs($this->s[$p-1]), abs($this->s[$p-2])), abs($e[$p-2])), abs($this->s[$k])), abs($e[$k]));
                    $sp   = $this->s[$p-1] / $scale;
                    $spm1 = $this->s[$p-2] / $scale;
                    $epm1 = $e[$p-2] / $scale;
                    $sk   = $this->s[$k] / $scale;
                    $ek   = $e[$k] / $scale;
                    $b    = (($spm1 + $sp) * ($spm1 - $sp) + $epm1 * $epm1) / 2.0;
                    $c    = ($sp * $epm1) * ($sp * $epm1);
                    $shift = 0.0;
                    if (($b != 0.0) || ($c != 0.0)) {
                        $shift = sqrt($b * $b + $c);
                        if ($b < 0.0) {
                            $shift = -$shift;
                        }
                        $shift = $c / ($b + $shift);
                    }
                    $f = ($sk + $sp) * ($sk - $sp) + $shift;
                    $g = $sk * $ek;
                    // Chase zeros.
                    for ($j = $k; $j < $p-1; ++$j) {
                        $t  = hypo($f, $g);
                        $cs = $f/$t;
                        $sn = $g/$t;
                        if ($j != $k) {
                            $e[$j-1] = $t;
                        }
                        $f = $cs * $this->s[$j] + $sn * $e[$j];
                        $e[$j] = $cs * $e[$j] - $sn * $this->s[$j];
                        $g = $sn * $this->s[$j+1];
                        $this->s[$j+1] = $cs * $this->s[$j+1];
                        if ($wantv) {
                            for ($i = 0; $i < $this->n; ++$i) {
                                $t = $cs * $this->V[$i][$j] + $sn * $this->V[$i][$j+1];
                                $this->V[$i][$j+1] = -$sn * $this->V[$i][$j] + $cs * $this->V[$i][$j+1];
                                $this->V[$i][$j] = $t;
                            }
                        }
                        $t = hypo($f, $g);
                        $cs = $f/$t;
                        $sn = $g/$t;
                        $this->s[$j] = $t;
                        $f = $cs * $e[$j] + $sn * $this->s[$j+1];
                        $this->s[$j+1] = -$sn * $e[$j] + $cs * $this->s[$j+1];
                        $g = $sn * $e[$j+1];
                        $e[$j+1] = $cs * $e[$j+1];
                        if ($wantu && ($j < $this->m - 1)) {
                            for ($i = 0; $i < $this->m; ++$i) {
                                $t = $cs * $this->U[$i][$j] + $sn * $this->U[$i][$j+1];
                                $this->U[$i][$j+1] = -$sn * $this->U[$i][$j] + $cs * $this->U[$i][$j+1];
                                $this->U[$i][$j] = $t;
                            }
                        }
                    }
                    $e[$p-2] = $f;
                    $iter = $iter + 1;
                    break;
                // Convergence.
                case 4:
                    // Make the singular values positive.
                    if ($this->s[$k] <= 0.0) {
                        $this->s[$k] = ($this->s[$k] < 0.0 ? -$this->s[$k] : 0.0);
                        if ($wantv) {
                            for ($i = 0; $i <= $pp; ++$i) {
                                $this->V[$i][$k] = -$this->V[$i][$k];
                            }
                        }
                    }
                    // Order the singular values.
                    while ($k < $pp) {
                        if ($this->s[$k] >= $this->s[$k+1]) {
                            break;
                        }
                        $t = $this->s[$k];
                        $this->s[$k] = $this->s[$k+1];
                        $this->s[$k+1] = $t;
                        if ($wantv and ($k < $this->n - 1)) {
                            for ($i = 0; $i < $this->n; ++$i) {
                                $t = $this->V[$i][$k+1];
                                $this->V[$i][$k+1] = $this->V[$i][$k];
                                $this->V[$i][$k] = $t;
                            }
                        }
                        if ($wantu and ($k < $this->m-1)) {
                            for ($i = 0; $i < $this->m; ++$i) {
                                $t = $this->U[$i][$k+1];
                                $this->U[$i][$k+1] = $this->U[$i][$k];
                                $this->U[$i][$k] = $t;
                            }
                        }
                        ++$k;
                    }
                    $iter = 0;
                    --$p;
                    break;
            } // end switch
        } // end while

    } // end constructor


    /**
     *    Return the left singular vectors
     *
     *    @access public
     *    @return U
     */
    public function getU()
    {
        return new Matrix($this->U, $this->m, min($this->m + 1, $this->n));
    }


    /**
     *    Return the right singular vectors
     *
     *    @access public
     *    @return V
     */
    public function getV()
    {
        return new Matrix($this->V);
    }


    /**
     *    Return the one-dimensional array of singular values
     *
     *    @access public
     *    @return diagonal of S.
     */
    public function getSingularValues()
    {
        return $this->s;
    }


    /**
     *    Return the diagonal matrix of singular values
     *
     *    @access public
     *    @return S
     */
    public function getS()
    {
        for ($i = 0; $i < $this->n; ++$i) {
            for ($j = 0; $j < $this->n; ++$j) {
                $S[$i][$j] = 0.0;
            }
            $S[$i][$i] = $this->s[$i];
        }
        return new Matrix($S);
    }


    /**
     *    Two norm
     *
     *    @access public
     *    @return max(S)
     */
    public function norm2()
    {
        return $this->s[0];
    }


    /**
     *    Two norm condition number
     *
     *    @access public
     *    @return max(S)/min(S)
     */
    public function cond()
    {
        return $this->s[0] / $this->s[min($this->m, $this->n) - 1];
    }


    /**
     *    Effective numerical matrix rank
     *
     *    @access public
     *    @return Number of nonnegligible singular values.
     */
    public function rank()
    {
        $eps = pow(2.0, -52.0);
        $tol = max($this->m, $this->n) * $this->s[0] * $eps;
        $r = 0;
        for ($i = 0; $i < count($this->s); ++$i) {
            if ($this->s[$i] > $tol) {
                ++$r;
            }
        }
        return $r;
    }
}