/* nag_dgeqlf (f08cec) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 23, 2011.
*/
#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf08.h>
#include <nagf16.h>
#include <nagx04.h>
int main(void)
{
/* Scalars */
Integer i, j, m, n, nrhs, pda, pdb;
Integer exit_status = 0;
/* Arrays */
double *a = 0, *b = 0, *rnorm = 0, *tau = 0;
/* Nag Types */
Nag_OrderType order;
NagError fail;
#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
#define B(I, J) b[(J - 1) * pdb + I - 1]
order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
#define B(I, J) b[(I - 1) * pdb + J - 1]
order = Nag_RowMajor;
#endif
INIT_FAIL(fail);
printf("nag_dgeqlf (f08cec) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%ld%ld%ld%*[^\n]", &m, &n, &nrhs);
/* Allocate memory */
if (!(a = NAG_ALLOC(m*n, double)) ||
!(b = NAG_ALLOC(m*nrhs, double)) ||
!(rnorm = NAG_ALLOC(nrhs, double)) ||
!(tau = NAG_ALLOC(n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
#ifdef NAG_COLUMN_MAJOR
pda = m;
pdb = m;
#else
pda = n;
pdb = nrhs;
#endif
/* Read A and B from data file */
for (i = 1; i <= m; ++i)
for (j = 1; j <= n; ++j)
scanf("%lf", &A(i, j));
scanf("%*[^\n]");
for (i = 1; i <= m; ++i)
for (j = 1; j <= nrhs; ++j)
scanf("%lf", &B(i, j));
scanf("%*[^\n]");
/* nag_dgeqlf (f08cec).
* Compute the QL factorization of A.
*/
nag_dgeqlf(order, m, n, a, pda, tau, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dgeqlf (f08cec).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* nag_dormql (f08cgc).
* Compute C = (C1) = (Q**T)*B, storing the result in B.
* (C2)
*/
nag_dormql(order, Nag_LeftSide, Nag_Trans, m, nrhs, n, a, pda, tau, b, pdb,
&fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dormql (f08cgc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* nag_dtrtrs (f07tec).
* Compute least-squares solutions by backsubstitution in
* L*X = C2.
*/
nag_dtrtrs(order, Nag_Lower, Nag_NoTrans, Nag_NonUnitDiag, n, nrhs,
&A(m - n + 1, 1), pda, &B(m - n + 1, 1), pdb, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dtrtrs (f07tec).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* nag_gen_real_mat_print (x04cac).
* Print least-squares solution(s).
*/
fflush(stdout);
nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs,
&B(m - n + 1, 1), pdb, "Least-squares solution(s)",
0, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
/* nag_dge_norm (f16rac).
* Compute and print estimates of the square roots of the residual
* sums of squares.
*/
for (j = 1; j <= nrhs; ++j) {
nag_dge_norm(order, Nag_FrobeniusNorm, m-n, 1, &B(1, j), pdb,
&rnorm[j-1], &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dge_norm (f16rac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
}
printf("\nSquare root(s) of the residual sum(s) of squares\n");
for (j = 0; j < nrhs; ++j)
printf("%11.2e%s", rnorm[j], (j+1)%7 == 0?"\n":" ");
END:
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(rnorm);
NAG_FREE(tau);
return exit_status;
}
#undef A
#undef B