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SPARK-1782: svd for sparse matrix using ARPACK
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copy ARPACK dsaupd/dseupd code from latest breeze
change RowMatrix to use sparse SVD
change tests for sparse SVD

All tests passed. I will run it against some large matrices.

Author: Li Pu <[email protected]>
Author: Xiangrui Meng <[email protected]>
Author: Li Pu <[email protected]>

Closes apache#964 from vrilleup/master and squashes the following commits:

7312ec1 [Li Pu] very minor comment fix
4c618e9 [Li Pu] Merge pull request apache#1 from mengxr/vrilleup-master
a461082 [Xiangrui Meng] make superscript show up correctly in doc
861ec48 [Xiangrui Meng] simplify axpy
62969fa [Xiangrui Meng] use BDV directly in symmetricEigs change the computation mode to local-svd, local-eigs, and dist-eigs update tests and docs
c273771 [Li Pu] automatically determine SVD compute mode and parameters
7148426 [Li Pu] improve RowMatrix multiply
5543cce [Li Pu] improve svd api
819824b [Li Pu] add flag for dense svd or sparse svd
eb15100 [Li Pu] fix binary compatibility
4c7aec3 [Li Pu] improve comments
e7850ed [Li Pu] use aggregate and axpy
827411b [Li Pu] fix EOF new line
9c80515 [Li Pu] use non-sparse implementation when k = n
fe983b0 [Li Pu] improve scala style
96d2ecb [Li Pu] improve eigenvalue sorting
e1db950 [Li Pu] SPARK-1782: svd for sparse matrix using ARPACK
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Li Pu authored and conviva-zz committed Sep 4, 2014
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.spark.mllib.linalg

import breeze.linalg.{DenseMatrix => BDM, DenseVector => BDV}
import com.github.fommil.netlib.ARPACK
import org.netlib.util.{intW, doubleW}

import org.apache.spark.annotation.Experimental

/**
* :: Experimental ::
* Compute eigen-decomposition.
*/
@Experimental
private[mllib] object EigenValueDecomposition {
/**
* Compute the leading k eigenvalues and eigenvectors on a symmetric square matrix using ARPACK.
* The caller needs to ensure that the input matrix is real symmetric. This function requires
* memory for `n*(4*k+4)` doubles.
*
* @param mul a function that multiplies the symmetric matrix with a DenseVector.
* @param n dimension of the square matrix (maximum Int.MaxValue).
* @param k number of leading eigenvalues required, 0 < k < n.
* @param tol tolerance of the eigs computation.
* @param maxIterations the maximum number of Arnoldi update iterations.
* @return a dense vector of eigenvalues in descending order and a dense matrix of eigenvectors
* (columns of the matrix).
* @note The number of computed eigenvalues might be smaller than k when some Ritz values do not
* satisfy the convergence criterion specified by tol (see ARPACK Users Guide, Chapter 4.6
* for more details). The maximum number of Arnoldi update iterations is set to 300 in this
* function.
*/
private[mllib] def symmetricEigs(
mul: BDV[Double] => BDV[Double],
n: Int,
k: Int,
tol: Double,
maxIterations: Int): (BDV[Double], BDM[Double]) = {
// TODO: remove this function and use eigs in breeze when switching breeze version
require(n > k, s"Number of required eigenvalues $k must be smaller than matrix dimension $n")

val arpack = ARPACK.getInstance()

// tolerance used in stopping criterion
val tolW = new doubleW(tol)
// number of desired eigenvalues, 0 < nev < n
val nev = new intW(k)
// nev Lanczos vectors are generated in the first iteration
// ncv-nev Lanczos vectors are generated in each subsequent iteration
// ncv must be smaller than n
val ncv = math.min(2 * k, n)

// "I" for standard eigenvalue problem, "G" for generalized eigenvalue problem
val bmat = "I"
// "LM" : compute the NEV largest (in magnitude) eigenvalues
val which = "LM"

var iparam = new Array[Int](11)
// use exact shift in each iteration
iparam(0) = 1
// maximum number of Arnoldi update iterations, or the actual number of iterations on output
iparam(2) = maxIterations
// Mode 1: A*x = lambda*x, A symmetric
iparam(6) = 1

var ido = new intW(0)
var info = new intW(0)
var resid = new Array[Double](n)
var v = new Array[Double](n * ncv)
var workd = new Array[Double](n * 3)
var workl = new Array[Double](ncv * (ncv + 8))
var ipntr = new Array[Int](11)

// call ARPACK's reverse communication, first iteration with ido = 0
arpack.dsaupd(ido, bmat, n, which, nev.`val`, tolW, resid, ncv, v, n, iparam, ipntr, workd,
workl, workl.length, info)

val w = BDV(workd)

// ido = 99 : done flag in reverse communication
while (ido.`val` != 99) {
if (ido.`val` != -1 && ido.`val` != 1) {
throw new IllegalStateException("ARPACK returns ido = " + ido.`val` +
" This flag is not compatible with Mode 1: A*x = lambda*x, A symmetric.")
}
// multiply working vector with the matrix
val inputOffset = ipntr(0) - 1
val outputOffset = ipntr(1) - 1
val x = w.slice(inputOffset, inputOffset + n)
val y = w.slice(outputOffset, outputOffset + n)
y := mul(x)
// call ARPACK's reverse communication
arpack.dsaupd(ido, bmat, n, which, nev.`val`, tolW, resid, ncv, v, n, iparam, ipntr,
workd, workl, workl.length, info)
}

if (info.`val` != 0) {
info.`val` match {
case 1 => throw new IllegalStateException("ARPACK returns non-zero info = " + info.`val` +
" Maximum number of iterations taken. (Refer ARPACK user guide for details)")
case 2 => throw new IllegalStateException("ARPACK returns non-zero info = " + info.`val` +
" No shifts could be applied. Try to increase NCV. " +
"(Refer ARPACK user guide for details)")
case _ => throw new IllegalStateException("ARPACK returns non-zero info = " + info.`val` +
" Please refer ARPACK user guide for error message.")
}
}

val d = new Array[Double](nev.`val`)
val select = new Array[Boolean](ncv)
// copy the Ritz vectors
val z = java.util.Arrays.copyOfRange(v, 0, nev.`val` * n)

// call ARPACK's post-processing for eigenvectors
arpack.dseupd(true, "A", select, d, z, n, 0.0, bmat, n, which, nev, tol, resid, ncv, v, n,
iparam, ipntr, workd, workl, workl.length, info)

// number of computed eigenvalues, might be smaller than k
val computed = iparam(4)

val eigenPairs = java.util.Arrays.copyOfRange(d, 0, computed).zipWithIndex.map { r =>
(r._1, java.util.Arrays.copyOfRange(z, r._2 * n, r._2 * n + n))
}

// sort the eigen-pairs in descending order
val sortedEigenPairs = eigenPairs.sortBy(- _._1)

// copy eigenvectors in descending order of eigenvalues
val sortedU = BDM.zeros[Double](n, computed)
sortedEigenPairs.zipWithIndex.foreach { r =>
val b = r._2 * n
var i = 0
while (i < n) {
sortedU.data(b + i) = r._1._2(i)
i += 1
}
}

(BDV[Double](sortedEigenPairs.map(_._1)), sortedU)
}
}
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