```/* nag_lapacklin_dptsvx (f07jbc) Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
*
* Mark 27.0, 2019.
*/

#include <stdio.h>
#include <nag.h>

int main(void)
{

/* Scalars */
double rcond;
Integer exit_status = 0, i, j, n, nrhs, pdb, pdx;
Nag_OrderType order;

/* Arrays */
double *b = 0, *berr = 0, *d = 0, *df = 0, *e = 0, *ef = 0, *ferr = 0;
double *work = 0, *x = 0;

/* Nag Types */
NagError fail;

#ifdef NAG_COLUMN_MAJOR
#define B(I, J) b[(J-1)*pdb + I - 1]
order = Nag_ColMajor;
#else
#define B(I, J) b[(I-1)*pdb + J - 1]
order = Nag_RowMajor;
#endif

INIT_FAIL(fail);

printf("nag_lapacklin_dptsvx (f07jbc) Example Program Results\n\n");

/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &n, &nrhs);
if (n < 0 || nrhs < 0) {
printf("Invalid n or nrhs\n");
exit_status = 1;
goto END;
}
/* Allocate memory */
if (!(b = NAG_ALLOC(n * nrhs, double)) ||
!(berr = NAG_ALLOC(nrhs, double)) ||
!(d = NAG_ALLOC(n, double)) ||
!(df = NAG_ALLOC(n, double)) ||
!(e = NAG_ALLOC(n - 1, double)) ||
!(ef = NAG_ALLOC(n - 1, double)) ||
!(ferr = NAG_ALLOC(nrhs, double)) ||
!(work = NAG_ALLOC(2 * n, double)) ||
!(x = NAG_ALLOC(n * nrhs, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
#ifdef NAG_COLUMN_MAJOR
pdb = n;
pdx = n;
#else
pdb = nrhs;
pdx = nrhs;
#endif

/* Read the lower bidiagonal part of the tridiagonal matrix A and the */
/* right hand side b from data file */
for (i = 0; i < n; ++i)
scanf("%lf", &d[i]);
scanf("%*[^\n]");
for (i = 0; i < n - 1; ++i)
scanf("%lf", &e[i]);
scanf("%*[^\n]");
for (i = 1; i <= n; ++i)
for (j = 1; j <= nrhs; ++j)
scanf("%lf", &B(i, j));
scanf("%*[^\n]");

/* Solve the equations AX = B for X using nag_lapacklin_dptsvx (f07jbc). */
nag_lapacklin_dptsvx(order, Nag_NotFactored, n, nrhs, d, e, df, ef, b, pdb, x, pdx,
&rcond, ferr, berr, &fail);
if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) {
printf("Error from nag_lapacklin_dptsvx (f07jbc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print solution using nag_file_print_matrix_real_gen (x04cac). */
fflush(stdout);
nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs,
x, pdx, "Solution(s)", 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;
goto END;
}

/* Print error bounds and condition number */
printf("\nBackward errors (machine-dependent)\n");
for (j = 0; j < nrhs; ++j)
printf("%11.1e%s", berr[j], j % 7 == 6 ? "\n" : " ");

printf("\n\nEstimated forward error bounds (machine-dependent)\n");
for (j = 0; j < nrhs; ++j)
printf("%11.1e%s", ferr[j], j % 7 == 6 ? "\n" : " ");

printf("\n\nEstimate of reciprocal condition number\n%11.1e\n", rcond);
if (fail.code == NE_SINGULAR) {
printf("Error from nag_lapacklin_dptsvx (f07jbc).\n%s\n", fail.message);
exit_status = 1;
}
END:
NAG_FREE(b);
NAG_FREE(berr);
NAG_FREE(d);
NAG_FREE(df);
NAG_FREE(e);
NAG_FREE(ef);
NAG_FREE(ferr);
NAG_FREE(work);
NAG_FREE(x);

return exit_status;
}

#undef B
```