135 lines
2.9 KiB
C++
135 lines
2.9 KiB
C++
/*
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* SPQRUtil.cpp
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*
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* Created on: Jul 1, 2010
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* Author: nikai
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* Description: the utility functions for SPQR
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*/
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#include <map>
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#include "SPQRUtil.h"
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using namespace std;
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#ifdef GT_USE_LAPACK
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namespace gtsam {
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/* ************************************************************************* */
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long* MakeStairs(Matrix& A) {
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const long m = A.size1();
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const long n = A.size2();
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long* Stair = new long[n];
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// record the starting pointer of each row
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double* a[m];
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list<int> remained;
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a[0] = A.data().begin();
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for(int i=0; i<m-1; i++) {
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a[i+1] = a[i] + n;
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remained.push_back(i);
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}
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remained.push_back(m-1);
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// reorder the rows
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int j;
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vector<int> sorted;
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list<int>::iterator itRemained;
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for(j = 0; j < min(m,n); ) {
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// remove the non-zero rows in the current column
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for(itRemained = remained.begin(); itRemained!=remained.end(); ) {
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if (*(a[*itRemained]) != 0) {
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sorted.push_back(*itRemained);
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itRemained = remained.erase(itRemained);
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} else {
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a[*itRemained]++;
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itRemained ++;
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}
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}
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// record the stair number
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Stair[j++] = m - remained.size();
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if(remained.empty()) break;
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}
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// all the remained columns have maximum stair
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for (; j<n; j++)
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Stair[j] = m;
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// copy the new row
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Matrix A_new = zeros(m,n);
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int offset[m];
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offset[0] = 0;
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for(int i=1; i<m; i++)
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offset[i] = offset[i-1] +n;
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vector<int>::const_iterator itSorted;
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double* ptr1 = A.data().begin();
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double* ptr2 = A_new.data().begin();
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int row = 0, sizeOfRow = n * sizeof(double);
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for(itSorted=sorted.begin(); itSorted!=sorted.end(); itSorted++, row++)
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memcpy(ptr2+offset[row], ptr1+offset[*itSorted], sizeOfRow);
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A = A_new;
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return Stair;
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}
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void printColumnMajor(const double* a, const long m, const long n) {
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for(int i=0; i<m; i++) {
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for(int j=0; j<n; j++)
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cout << a[j*m+i] << "\t";
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cout << endl;
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}
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}
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/* ************************************************************************* */
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void householder_spqr(Matrix &A, long* Stair) {
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long m = A.size1();
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long n = A.size2();
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if (Stair == NULL) {
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Stair = new long[n];
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for(int j=0; j<n; j++)
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Stair[j] = m;
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}
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// convert from row major to column major
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double a[m*n]; int k = 0;
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for(int j=0; j<n; j++)
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for(int i=0; i<m; i++, k++)
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a[k] = A(i,j);
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long npiv = min(m,n);
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double tol = -1; long ntol = -1; // no tolerance is used
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long fchunk = m < 32 ? m : 32;
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char Rdead[npiv];
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double Tau[n];
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long b = min(fchunk, min(n, m));
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double W[b*(n+b)];
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double wscale = 0;
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double wssq = 0;
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cholmod_common cc;
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cholmod_l_start(&cc);
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long rank = spqr_front<double>(m, n, npiv, tol, ntol, fchunk,
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a, Stair, Rdead, Tau, W, &wscale, &wssq, &cc);
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long k0 = 0;
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long j0;
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memset(A.data().begin(), 0, m*n*sizeof(double));
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for(long j=0; j<n; j++, k0+=m) {
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k = k0;
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j0 = min(j+1,m);
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for(int i=0; i<j0; i++, k++)
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A(i,j) = a[k];
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}
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delete []Stair;
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cholmod_l_finish(&cc);
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}
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} // namespace gtsam
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#endif
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