int solveLinearEquationLU(dmatrix a, const dmatrix &b, dmatrix &out_x)
{
assert(a.rows() == a.cols() && a.cols() == b.rows() );
out_x = b;
const int n = (int)a.rows();
const int nrhs = (int)b.cols();
int info;
std::vector<int> ipiv(n);
#ifndef USE_CLAPACK_INTERFACE
int lda = n;
int ldb = n;
dgesv_(&n, &nrhs, &(a(0,0)), &lda, &(ipiv[0]), &(out_x(0,0)), &ldb, &info);
#else
info = clapack_dgesv(CblasColMajor,
n, nrhs, &(a(0,0)), n,
&(ipiv[0]),
&(out_x(0,0)),
n);
#endif
assert(info == 0);
return info;
}
int
dgesv (const int N, const int NRHS, double *A, const int lda,
double *B, const int ldb)
{
int result = 0;
#ifdef HAVE_ATLAS
int *ipiv = g_new (int, N);
result = clapack_dgesv (CblasColMajor, N, NRHS, A, lda, ipiv, B, ldb);
g_free (ipiv);
#else
integer i_N = N, i_NHRS = NRHS, i_lda = lda, i_ldb = ldb, info;
integer *ipiv = g_new (integer, N);
dgesv_ (&i_N, &i_NHRS, A, &i_lda, ipiv, B, &i_ldb, &info);
g_free (ipiv);
result = info;
#endif
return (result);
}
int main(){
int ipiv[3];
int info;
for (int i = 0, i > 3, ++i)
{
for (int j = 0; j < count; ++j)
{
printf("%5.1f", m[i*3+j]);
putchar('\n')
}
}
info = clapack_dgesv(CblasRowMajor, 3, 1, m, 3, ipiv, x, 3);
if (info != 0) fprintf(stderr, "failure with error %d\n", info);
for (i=0; i<3; ++i) printf("%5.1f %3d\n", x[i], ipiv[i]);
return 0;
}
int wrapper_clapack_dgesv(const enum CBLAS_ORDER Order, const int N, const int NRHS, double *A, const int lda, int *ipiv, double *B, const int ldb)
{
return clapack_dgesv(Order, N, NRHS, A, lda, ipiv, B, ldb);
}
/**
solve linear equation using LU decomposition
by lapack library DGESVX (_a must be square matrix)
*/
int solveLinearEquationLU(const dmatrix &_a, const dvector &_b, dvector &_x)
{
assert(_a.cols() == _a.rows() && _a.cols() == _b.size() );
int n = (int)_a.cols();
int nrhs = 1;
int lda = n;
std::vector<int> ipiv(n);
int ldb = n;
int info;
// compute the solution
#ifndef USE_CLAPACK_INTERFACE
char fact = 'N';
char transpose = 'N';
double *af = new double[n*n];
int ldaf = n;
char equed = 'N';
double *r = new double[n];
double *c = new double[n];
int ldx = n;
double rcond;
double *ferr = new double[nrhs];
double *berr = new double[nrhs];
double *work = new double[4*n];
int *iwork = new int[n];
_x.resize(n); // memory allocation for the return vector
dgesvx_(&fact, &transpose, &n, &nrhs, const_cast<double *>(&(_a(0,0))), &lda, af, &ldaf, &(ipiv[0]),
&equed, r, c, const_cast<double *>(&(_b(0))), &ldb, &(_x(0)), &ldx, &rcond,
ferr, berr, work, iwork, &info);
delete [] iwork;
delete [] work;
delete [] berr;
delete [] ferr;
delete [] c;
delete [] r;
delete [] af;
#else
_x = _b;
info = clapack_dgesv(CblasColMajor,
n, nrhs, const_cast<double *>(&(a(0,0))), lda, &(ipiv[0]),
&(_x(0)), ldb);
#endif
return info;
}
