f08ajce.c

/* nag_lapackeig_dorglq (f08ajc) Example Program.
 *
 * Copyright 2025 Numerical Algorithms Group.
 *
 * Mark 31.1, 2025.
 */
#include<nag.h>
#include<stdio.h>
intmain(void){
/* Scalars */
Integeri,j,m,n,pda;
Integerexit_status=0;
NagErrorfail;
Nag_OrderTypeorder;
/* Arrays */
char*title=0;
double*a=0,*tau=0;
#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
order=Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
order=Nag_RowMajor;
#endif
INIT_FAIL(fail);
printf("nag_lapackeig_dorglq (f08ajc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%"NAG_IFMT"%"NAG_IFMT"%*[^\n] ",&m,&n);
#ifdef NAG_COLUMN_MAJOR
pda=m;
#else
pda=n;
#endif
/* Allocate memory */
if(!(title=NAG_ALLOC(31,char))||!(a=NAG_ALLOC(m*n,double))||
!(tau=NAG_ALLOC(m,double))){
printf("Allocation failure\n");
exit_status=-1;
gotoEND;
}
/* Read A from data file */
for(i=1;i<=m;++i){
for(j=1;j<=n;++j)
scanf("%lf",&A(i,j));
}
scanf("%*[^\n] ");
/* Compute the LQ factorization of A */
/* nag_lapackeig_dgelqf (f08ahc).
 * LQ factorization of real general rectangular matrix
 */
nag_lapackeig_dgelqf(order,m,n,a,pda,tau,&fail);
if(fail.code!=NE_NOERROR){
printf("Error from nag_lapackeig_dgelqf (f08ahc).\n%s\n",fail.message);
exit_status=1;
gotoEND;
}
/* Form the leading M rows of Q explicitly */
/* nag_lapackeig_dorglq (f08ajc).
 * Form all or part of orthogonal Q from LQ factorization
 * determined by nag_lapackeig_dgelqf (f08ahc)
 */
nag_lapackeig_dorglq(order,m,n,m,a,pda,tau,&fail);
if(fail.code!=NE_NOERROR){
printf("Error from nag_lapackeig_dorglq (f08ajc).\n%s\n",fail.message);
exit_status=1;
gotoEND;
}
/* Print the leading M rows of Q only */
sprintf(title,"The leading %2"NAG_IFMT" rows of Q\n",m);
/* nag_file_print_matrix_real_gen (x04cac).
 * Print real general matrix (easy-to-use)
 */
fflush(stdout);
nag_file_print_matrix_real_gen(order,Nag_GeneralMatrix,Nag_NonUnitDiag,m,
n,a,pda,title,0,&fail);
if(fail.code!=NE_NOERROR){
printf("Error from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
fail.message);
exit_status=1;
gotoEND;
}
END:
NAG_FREE(title);
NAG_FREE(a);
NAG_FREE(tau);
returnexit_status;
}