/usr/include/linbox/ffpack/ffpack_minpoly.inl is in liblinbox-dev 1.1.6~rc0-4.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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/* ffpack/ffpack_minpoly.inl
* Copyright (C) 2005 Clement Pernet
*
* Written by Clement Pernet <Clement.Pernet@imag.fr>
*
* See COPYING for license information.
*/
template <class Field, class Polynomial>
Polynomial&
FFPACK::MinPoly( const Field& F, Polynomial& minP, const size_t N,
const typename Field::Element *A, const size_t lda,
typename Field::Element* X, const size_t ldx,
size_t* P,
const FFPACK_MINPOLY_TAG MinTag = FfpackDense,
const size_t kg_mc =0,
const size_t kg_mb=0,
const size_t kg_j=0 ){
typedef typename Field::Element elt;
static elt one,zero;
F.init( one, 1.0 );
F.init( zero, 0.0 );
// nRow is the number of row in the krylov base already computed
size_t j, k, nRow = 2;
typename Polynomial::iterator it;
elt* Xi, *Ui;
typename Field::RandIter g (F);
bool KeepOn=true;
elt* U = new elt[N];
// Picking a non zero vector
do{
for (Ui=U, Xi = X; Ui<U+N; ++Ui, ++Xi){
g.random (*Ui);
*Xi = *Ui;
if (!F.isZero(*Ui))
KeepOn = false;
}
}while(KeepOn);
nRow = 1;
// LUP factorization of the Krylov Base Matrix
k = LUdivine_construct (F, FflasUnit, N+1, N, A, lda, X, ldx, U, P, true,
MinTag, kg_mc, kg_mb, kg_j);
//delete[] U;
minP.resize(k+1);
minP[k] = one;
if ( (k==1) && F.isZero(*(X+ldx))){ // minpoly is X
delete[] U;
for (size_t i=0; i<k; ++i)
minP[i] = zero;
return minP;
}
// U contains the k first coefs of the minpoly
//elt* m= new elt[k];
fcopy( F, k, U, 1, X+k*ldx, 1);
ftrsv( F, FflasLower, FflasTrans, FflasNonUnit, k, X, ldx, U, 1);
it = minP.begin();
for (j=0; j<k; ++j, it++){
F.neg(*it, U[j]);
}
delete[] U;
return minP;
}
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