14 typedef long long BLASLONG;
15 typedef unsigned long long BLASULONG;
17 typedef long BLASLONG;
18 typedef unsigned long BLASULONG;
22 typedef BLASLONG blasint;
24 #define blasabs(x) llabs(x)
26 #define blasabs(x) labs(x)
30 #define blasabs(x) abs(x)
33 typedef blasint integer;
35 typedef unsigned int uinteger;
36 typedef char *address;
37 typedef short int shortint;
39 typedef double doublereal;
40 typedef struct { real r, i; } complex;
41 typedef struct { doublereal r, i; } doublecomplex;
43 static inline _Fcomplex Cf(complex *z) {_Fcomplex zz={z->r , z->i}; return zz;}
44 static inline _Dcomplex Cd(doublecomplex *z) {_Dcomplex zz={z->r , z->i};return zz;}
45 static inline _Fcomplex * _pCf(complex *z) {return (_Fcomplex*)z;}
46 static inline _Dcomplex * _pCd(doublecomplex *z) {return (_Dcomplex*)z;}
48 static inline _Complex float Cf(complex *z) {return z->r + z->i*_Complex_I;}
49 static inline _Complex double Cd(doublecomplex *z) {return z->r + z->i*_Complex_I;}
50 static inline _Complex float * _pCf(complex *z) {return (_Complex float*)z;}
51 static inline _Complex double * _pCd(doublecomplex *z) {return (_Complex double*)z;}
53 #define pCf(z) (*_pCf(z))
54 #define pCd(z) (*_pCd(z))
56 typedef short int shortlogical;
57 typedef char logical1;
58 typedef char integer1;
63 /* Extern is for use with -E */
74 /*external read, write*/
83 /*internal read, write*/
113 /*rewind, backspace, endfile*/
125 ftnint *inex; /*parameters in standard's order*/
151 union Multitype { /* for multiple entry points */
162 typedef union Multitype Multitype;
164 struct Vardesc { /* for Namelist */
170 typedef struct Vardesc Vardesc;
177 typedef struct Namelist Namelist;
179 #define abs(x) ((x) >= 0 ? (x) : -(x))
180 #define dabs(x) (fabs(x))
181 #define f2cmin(a,b) ((a) <= (b) ? (a) : (b))
182 #define f2cmax(a,b) ((a) >= (b) ? (a) : (b))
183 #define dmin(a,b) (f2cmin(a,b))
184 #define dmax(a,b) (f2cmax(a,b))
185 #define bit_test(a,b) ((a) >> (b) & 1)
186 #define bit_clear(a,b) ((a) & ~((uinteger)1 << (b)))
187 #define bit_set(a,b) ((a) | ((uinteger)1 << (b)))
189 #define abort_() { sig_die("Fortran abort routine called", 1); }
190 #define c_abs(z) (cabsf(Cf(z)))
191 #define c_cos(R,Z) { pCf(R)=ccos(Cf(Z)); }
193 #define c_div(c, a, b) {Cf(c)._Val[0] = (Cf(a)._Val[0]/Cf(b)._Val[0]); Cf(c)._Val[1]=(Cf(a)._Val[1]/Cf(b)._Val[1]);}
194 #define z_div(c, a, b) {Cd(c)._Val[0] = (Cd(a)._Val[0]/Cd(b)._Val[0]); Cd(c)._Val[1]=(Cd(a)._Val[1]/df(b)._Val[1]);}
196 #define c_div(c, a, b) {pCf(c) = Cf(a)/Cf(b);}
197 #define z_div(c, a, b) {pCd(c) = Cd(a)/Cd(b);}
199 #define c_exp(R, Z) {pCf(R) = cexpf(Cf(Z));}
200 #define c_log(R, Z) {pCf(R) = clogf(Cf(Z));}
201 #define c_sin(R, Z) {pCf(R) = csinf(Cf(Z));}
202 //#define c_sqrt(R, Z) {*(R) = csqrtf(Cf(Z));}
203 #define c_sqrt(R, Z) {pCf(R) = csqrtf(Cf(Z));}
204 #define d_abs(x) (fabs(*(x)))
205 #define d_acos(x) (acos(*(x)))
206 #define d_asin(x) (asin(*(x)))
207 #define d_atan(x) (atan(*(x)))
208 #define d_atn2(x, y) (atan2(*(x),*(y)))
209 #define d_cnjg(R, Z) { pCd(R) = conj(Cd(Z)); }
210 #define r_cnjg(R, Z) { pCf(R) = conjf(Cf(Z)); }
211 #define d_cos(x) (cos(*(x)))
212 #define d_cosh(x) (cosh(*(x)))
213 #define d_dim(__a, __b) ( *(__a) > *(__b) ? *(__a) - *(__b) : 0.0 )
214 #define d_exp(x) (exp(*(x)))
215 #define d_imag(z) (cimag(Cd(z)))
216 #define r_imag(z) (cimagf(Cf(z)))
217 #define d_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
218 #define r_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
219 #define d_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
220 #define r_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
221 #define d_log(x) (log(*(x)))
222 #define d_mod(x, y) (fmod(*(x), *(y)))
223 #define u_nint(__x) ((__x)>=0 ? floor((__x) + .5) : -floor(.5 - (__x)))
224 #define d_nint(x) u_nint(*(x))
225 #define u_sign(__a,__b) ((__b) >= 0 ? ((__a) >= 0 ? (__a) : -(__a)) : -((__a) >= 0 ? (__a) : -(__a)))
226 #define d_sign(a,b) u_sign(*(a),*(b))
227 #define r_sign(a,b) u_sign(*(a),*(b))
228 #define d_sin(x) (sin(*(x)))
229 #define d_sinh(x) (sinh(*(x)))
230 #define d_sqrt(x) (sqrt(*(x)))
231 #define d_tan(x) (tan(*(x)))
232 #define d_tanh(x) (tanh(*(x)))
233 #define i_abs(x) abs(*(x))
234 #define i_dnnt(x) ((integer)u_nint(*(x)))
235 #define i_len(s, n) (n)
236 #define i_nint(x) ((integer)u_nint(*(x)))
237 #define i_sign(a,b) ((integer)u_sign((integer)*(a),(integer)*(b)))
238 #define pow_dd(ap, bp) ( pow(*(ap), *(bp)))
239 #define pow_si(B,E) spow_ui(*(B),*(E))
240 #define pow_ri(B,E) spow_ui(*(B),*(E))
241 #define pow_di(B,E) dpow_ui(*(B),*(E))
242 #define pow_zi(p, a, b) {pCd(p) = zpow_ui(Cd(a), *(b));}
243 #define pow_ci(p, a, b) {pCf(p) = cpow_ui(Cf(a), *(b));}
244 #define pow_zz(R,A,B) {pCd(R) = cpow(Cd(A),*(B));}
245 #define s_cat(lpp, rpp, rnp, np, llp) { ftnlen i, nc, ll; char *f__rp, *lp; ll = (llp); lp = (lpp); for(i=0; i < (int)*(np); ++i) { nc = ll; if((rnp)[i] < nc) nc = (rnp)[i]; ll -= nc; f__rp = (rpp)[i]; while(--nc >= 0) *lp++ = *(f__rp)++; } while(--ll >= 0) *lp++ = ' '; }
246 #define s_cmp(a,b,c,d) ((integer)strncmp((a),(b),f2cmin((c),(d))))
247 #define s_copy(A,B,C,D) { int __i,__m; for (__i=0, __m=f2cmin((C),(D)); __i<__m && (B)[__i] != 0; ++__i) (A)[__i] = (B)[__i]; }
248 #define sig_die(s, kill) { exit(1); }
249 #define s_stop(s, n) {exit(0);}
250 static char junk[] = "\n@(#)LIBF77 VERSION 19990503\n";
251 #define z_abs(z) (cabs(Cd(z)))
252 #define z_exp(R, Z) {pCd(R) = cexp(Cd(Z));}
253 #define z_sqrt(R, Z) {pCd(R) = csqrt(Cd(Z));}
254 #define myexit_() break;
255 #define mycycle() continue;
256 #define myceiling(w) {ceil(w)}
257 #define myhuge(w) {HUGE_VAL}
258 //#define mymaxloc_(w,s,e,n) {if (sizeof(*(w)) == sizeof(double)) dmaxloc_((w),*(s),*(e),n); else dmaxloc_((w),*(s),*(e),n);}
259 #define mymaxloc(w,s,e,n) {dmaxloc_(w,*(s),*(e),n)}
261 /* procedure parameter types for -A and -C++ */
263 #define F2C_proc_par_types 1
265 typedef logical (*L_fp)(...);
267 typedef logical (*L_fp)();
270 static float spow_ui(float x, integer n) {
271 float pow=1.0; unsigned long int u;
273 if(n < 0) n = -n, x = 1/x;
282 static double dpow_ui(double x, integer n) {
283 double pow=1.0; unsigned long int u;
285 if(n < 0) n = -n, x = 1/x;
295 static _Fcomplex cpow_ui(complex x, integer n) {
296 complex pow={1.0,0.0}; unsigned long int u;
298 if(n < 0) n = -n, x.r = 1/x.r, x.i=1/x.i;
300 if(u & 01) pow.r *= x.r, pow.i *= x.i;
301 if(u >>= 1) x.r *= x.r, x.i *= x.i;
305 _Fcomplex p={pow.r, pow.i};
309 static _Complex float cpow_ui(_Complex float x, integer n) {
310 _Complex float pow=1.0; unsigned long int u;
312 if(n < 0) n = -n, x = 1/x;
323 static _Dcomplex zpow_ui(_Dcomplex x, integer n) {
324 _Dcomplex pow={1.0,0.0}; unsigned long int u;
326 if(n < 0) n = -n, x._Val[0] = 1/x._Val[0], x._Val[1] =1/x._Val[1];
328 if(u & 01) pow._Val[0] *= x._Val[0], pow._Val[1] *= x._Val[1];
329 if(u >>= 1) x._Val[0] *= x._Val[0], x._Val[1] *= x._Val[1];
333 _Dcomplex p = {pow._Val[0], pow._Val[1]};
337 static _Complex double zpow_ui(_Complex double x, integer n) {
338 _Complex double pow=1.0; unsigned long int u;
340 if(n < 0) n = -n, x = 1/x;
350 static integer pow_ii(integer x, integer n) {
351 integer pow; unsigned long int u;
353 if (n == 0 || x == 1) pow = 1;
354 else if (x != -1) pow = x == 0 ? 1/x : 0;
357 if ((n > 0) || !(n == 0 || x == 1 || x != -1)) {
367 static integer dmaxloc_(double *w, integer s, integer e, integer *n)
369 double m; integer i, mi;
370 for(m=w[s-1], mi=s, i=s+1; i<=e; i++)
371 if (w[i-1]>m) mi=i ,m=w[i-1];
374 static integer smaxloc_(float *w, integer s, integer e, integer *n)
376 float m; integer i, mi;
377 for(m=w[s-1], mi=s, i=s+1; i<=e; i++)
378 if (w[i-1]>m) mi=i ,m=w[i-1];
381 static inline void cdotc_(complex *z, integer *n_, complex *x, integer *incx_, complex *y, integer *incy_) {
382 integer n = *n_, incx = *incx_, incy = *incy_, i;
384 _Fcomplex zdotc = {0.0, 0.0};
385 if (incx == 1 && incy == 1) {
386 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
387 zdotc._Val[0] += conjf(Cf(&x[i]))._Val[0] * Cf(&y[i])._Val[0];
388 zdotc._Val[1] += conjf(Cf(&x[i]))._Val[1] * Cf(&y[i])._Val[1];
391 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
392 zdotc._Val[0] += conjf(Cf(&x[i*incx]))._Val[0] * Cf(&y[i*incy])._Val[0];
393 zdotc._Val[1] += conjf(Cf(&x[i*incx]))._Val[1] * Cf(&y[i*incy])._Val[1];
399 _Complex float zdotc = 0.0;
400 if (incx == 1 && incy == 1) {
401 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
402 zdotc += conjf(Cf(&x[i])) * Cf(&y[i]);
405 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
406 zdotc += conjf(Cf(&x[i*incx])) * Cf(&y[i*incy]);
412 static inline void zdotc_(doublecomplex *z, integer *n_, doublecomplex *x, integer *incx_, doublecomplex *y, integer *incy_) {
413 integer n = *n_, incx = *incx_, incy = *incy_, i;
415 _Dcomplex zdotc = {0.0, 0.0};
416 if (incx == 1 && incy == 1) {
417 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
418 zdotc._Val[0] += conj(Cd(&x[i]))._Val[0] * Cd(&y[i])._Val[0];
419 zdotc._Val[1] += conj(Cd(&x[i]))._Val[1] * Cd(&y[i])._Val[1];
422 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
423 zdotc._Val[0] += conj(Cd(&x[i*incx]))._Val[0] * Cd(&y[i*incy])._Val[0];
424 zdotc._Val[1] += conj(Cd(&x[i*incx]))._Val[1] * Cd(&y[i*incy])._Val[1];
430 _Complex double zdotc = 0.0;
431 if (incx == 1 && incy == 1) {
432 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
433 zdotc += conj(Cd(&x[i])) * Cd(&y[i]);
436 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
437 zdotc += conj(Cd(&x[i*incx])) * Cd(&y[i*incy]);
443 static inline void cdotu_(complex *z, integer *n_, complex *x, integer *incx_, complex *y, integer *incy_) {
444 integer n = *n_, incx = *incx_, incy = *incy_, i;
446 _Fcomplex zdotc = {0.0, 0.0};
447 if (incx == 1 && incy == 1) {
448 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
449 zdotc._Val[0] += Cf(&x[i])._Val[0] * Cf(&y[i])._Val[0];
450 zdotc._Val[1] += Cf(&x[i])._Val[1] * Cf(&y[i])._Val[1];
453 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
454 zdotc._Val[0] += Cf(&x[i*incx])._Val[0] * Cf(&y[i*incy])._Val[0];
455 zdotc._Val[1] += Cf(&x[i*incx])._Val[1] * Cf(&y[i*incy])._Val[1];
461 _Complex float zdotc = 0.0;
462 if (incx == 1 && incy == 1) {
463 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
464 zdotc += Cf(&x[i]) * Cf(&y[i]);
467 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
468 zdotc += Cf(&x[i*incx]) * Cf(&y[i*incy]);
474 static inline void zdotu_(doublecomplex *z, integer *n_, doublecomplex *x, integer *incx_, doublecomplex *y, integer *incy_) {
475 integer n = *n_, incx = *incx_, incy = *incy_, i;
477 _Dcomplex zdotc = {0.0, 0.0};
478 if (incx == 1 && incy == 1) {
479 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
480 zdotc._Val[0] += Cd(&x[i])._Val[0] * Cd(&y[i])._Val[0];
481 zdotc._Val[1] += Cd(&x[i])._Val[1] * Cd(&y[i])._Val[1];
484 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
485 zdotc._Val[0] += Cd(&x[i*incx])._Val[0] * Cd(&y[i*incy])._Val[0];
486 zdotc._Val[1] += Cd(&x[i*incx])._Val[1] * Cd(&y[i*incy])._Val[1];
492 _Complex double zdotc = 0.0;
493 if (incx == 1 && incy == 1) {
494 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
495 zdotc += Cd(&x[i]) * Cd(&y[i]);
498 for (i=0;i<n;i++) { /* zdotc = zdotc + dconjg(x(i))* y(i) */
499 zdotc += Cd(&x[i*incx]) * Cd(&y[i*incy]);
505 /* -- translated by f2c (version 20000121).
506 You must link the resulting object file with the libraries:
507 -lf2c -lm (in that order)
513 /* Table of constant values */
515 static integer c__1 = 1;
517 /* > \brief <b> DGTSVX computes the solution to system of linear equations A * X = B for GT matrices </b> */
519 /* =========== DOCUMENTATION =========== */
521 /* Online html documentation available at */
522 /* http://www.netlib.org/lapack/explore-html/ */
525 /* > Download DGTSVX + dependencies */
526 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dgtsvx.
529 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dgtsvx.
532 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dgtsvx.
540 /* SUBROUTINE DGTSVX( FACT, TRANS, N, NRHS, DL, D, DU, DLF, DF, DUF, */
541 /* DU2, IPIV, B, LDB, X, LDX, RCOND, FERR, BERR, */
542 /* WORK, IWORK, INFO ) */
544 /* CHARACTER FACT, TRANS */
545 /* INTEGER INFO, LDB, LDX, N, NRHS */
546 /* DOUBLE PRECISION RCOND */
547 /* INTEGER IPIV( * ), IWORK( * ) */
548 /* DOUBLE PRECISION B( LDB, * ), BERR( * ), D( * ), DF( * ), */
549 /* $ DL( * ), DLF( * ), DU( * ), DU2( * ), DUF( * ), */
550 /* $ FERR( * ), WORK( * ), X( LDX, * ) */
553 /* > \par Purpose: */
558 /* > DGTSVX uses the LU factorization to compute the solution to a real */
559 /* > system of linear equations A * X = B or A**T * X = B, */
560 /* > where A is a tridiagonal matrix of order N and X and B are N-by-NRHS */
563 /* > Error bounds on the solution and a condition estimate are also */
567 /* > \par Description: */
568 /* ================= */
572 /* > The following steps are performed: */
574 /* > 1. If FACT = 'N', the LU decomposition is used to factor the matrix A */
575 /* > as A = L * U, where L is a product of permutation and unit lower */
576 /* > bidiagonal matrices and U is upper triangular with nonzeros in */
577 /* > only the main diagonal and first two superdiagonals. */
579 /* > 2. If some U(i,i)=0, so that U is exactly singular, then the routine */
580 /* > returns with INFO = i. Otherwise, the factored form of A is used */
581 /* > to estimate the condition number of the matrix A. If the */
582 /* > reciprocal of the condition number is less than machine precision, */
583 /* > INFO = N+1 is returned as a warning, but the routine still goes on */
584 /* > to solve for X and compute error bounds as described below. */
586 /* > 3. The system of equations is solved for X using the factored form */
589 /* > 4. Iterative refinement is applied to improve the computed solution */
590 /* > matrix and calculate error bounds and backward error estimates */
597 /* > \param[in] FACT */
599 /* > FACT is CHARACTER*1 */
600 /* > Specifies whether or not the factored form of A has been */
601 /* > supplied on entry. */
602 /* > = 'F': DLF, DF, DUF, DU2, and IPIV contain the factored */
603 /* > form of A; DL, D, DU, DLF, DF, DUF, DU2 and IPIV */
604 /* > will not be modified. */
605 /* > = 'N': The matrix will be copied to DLF, DF, and DUF */
606 /* > and factored. */
609 /* > \param[in] TRANS */
611 /* > TRANS is CHARACTER*1 */
612 /* > Specifies the form of the system of equations: */
613 /* > = 'N': A * X = B (No transpose) */
614 /* > = 'T': A**T * X = B (Transpose) */
615 /* > = 'C': A**H * X = B (Conjugate transpose = Transpose) */
621 /* > The order of the matrix A. N >= 0. */
624 /* > \param[in] NRHS */
626 /* > NRHS is INTEGER */
627 /* > The number of right hand sides, i.e., the number of columns */
628 /* > of the matrix B. NRHS >= 0. */
631 /* > \param[in] DL */
633 /* > DL is DOUBLE PRECISION array, dimension (N-1) */
634 /* > The (n-1) subdiagonal elements of A. */
639 /* > D is DOUBLE PRECISION array, dimension (N) */
640 /* > The n diagonal elements of A. */
643 /* > \param[in] DU */
645 /* > DU is DOUBLE PRECISION array, dimension (N-1) */
646 /* > The (n-1) superdiagonal elements of A. */
649 /* > \param[in,out] DLF */
651 /* > DLF is DOUBLE PRECISION array, dimension (N-1) */
652 /* > If FACT = 'F', then DLF is an input argument and on entry */
653 /* > contains the (n-1) multipliers that define the matrix L from */
654 /* > the LU factorization of A as computed by DGTTRF. */
656 /* > If FACT = 'N', then DLF is an output argument and on exit */
657 /* > contains the (n-1) multipliers that define the matrix L from */
658 /* > the LU factorization of A. */
661 /* > \param[in,out] DF */
663 /* > DF is DOUBLE PRECISION array, dimension (N) */
664 /* > If FACT = 'F', then DF is an input argument and on entry */
665 /* > contains the n diagonal elements of the upper triangular */
666 /* > matrix U from the LU factorization of A. */
668 /* > If FACT = 'N', then DF is an output argument and on exit */
669 /* > contains the n diagonal elements of the upper triangular */
670 /* > matrix U from the LU factorization of A. */
673 /* > \param[in,out] DUF */
675 /* > DUF is DOUBLE PRECISION array, dimension (N-1) */
676 /* > If FACT = 'F', then DUF is an input argument and on entry */
677 /* > contains the (n-1) elements of the first superdiagonal of U. */
679 /* > If FACT = 'N', then DUF is an output argument and on exit */
680 /* > contains the (n-1) elements of the first superdiagonal of U. */
683 /* > \param[in,out] DU2 */
685 /* > DU2 is DOUBLE PRECISION array, dimension (N-2) */
686 /* > If FACT = 'F', then DU2 is an input argument and on entry */
687 /* > contains the (n-2) elements of the second superdiagonal of */
690 /* > If FACT = 'N', then DU2 is an output argument and on exit */
691 /* > contains the (n-2) elements of the second superdiagonal of */
695 /* > \param[in,out] IPIV */
697 /* > IPIV is INTEGER array, dimension (N) */
698 /* > If FACT = 'F', then IPIV is an input argument and on entry */
699 /* > contains the pivot indices from the LU factorization of A as */
700 /* > computed by DGTTRF. */
702 /* > If FACT = 'N', then IPIV is an output argument and on exit */
703 /* > contains the pivot indices from the LU factorization of A; */
704 /* > row i of the matrix was interchanged with row IPIV(i). */
705 /* > IPIV(i) will always be either i or i+1; IPIV(i) = i indicates */
706 /* > a row interchange was not required. */
711 /* > B is DOUBLE PRECISION array, dimension (LDB,NRHS) */
712 /* > The N-by-NRHS right hand side matrix B. */
715 /* > \param[in] LDB */
717 /* > LDB is INTEGER */
718 /* > The leading dimension of the array B. LDB >= f2cmax(1,N). */
721 /* > \param[out] X */
723 /* > X is DOUBLE PRECISION array, dimension (LDX,NRHS) */
724 /* > If INFO = 0 or INFO = N+1, the N-by-NRHS solution matrix X. */
727 /* > \param[in] LDX */
729 /* > LDX is INTEGER */
730 /* > The leading dimension of the array X. LDX >= f2cmax(1,N). */
733 /* > \param[out] RCOND */
735 /* > RCOND is DOUBLE PRECISION */
736 /* > The estimate of the reciprocal condition number of the matrix */
737 /* > A. If RCOND is less than the machine precision (in */
738 /* > particular, if RCOND = 0), the matrix is singular to working */
739 /* > precision. This condition is indicated by a return code of */
743 /* > \param[out] FERR */
745 /* > FERR is DOUBLE PRECISION array, dimension (NRHS) */
746 /* > The estimated forward error bound for each solution vector */
747 /* > X(j) (the j-th column of the solution matrix X). */
748 /* > If XTRUE is the true solution corresponding to X(j), FERR(j) */
749 /* > is an estimated upper bound for the magnitude of the largest */
750 /* > element in (X(j) - XTRUE) divided by the magnitude of the */
751 /* > largest element in X(j). The estimate is as reliable as */
752 /* > the estimate for RCOND, and is almost always a slight */
753 /* > overestimate of the true error. */
756 /* > \param[out] BERR */
758 /* > BERR is DOUBLE PRECISION array, dimension (NRHS) */
759 /* > The componentwise relative backward error of each solution */
760 /* > vector X(j) (i.e., the smallest relative change in */
761 /* > any element of A or B that makes X(j) an exact solution). */
764 /* > \param[out] WORK */
766 /* > WORK is DOUBLE PRECISION array, dimension (3*N) */
769 /* > \param[out] IWORK */
771 /* > IWORK is INTEGER array, dimension (N) */
774 /* > \param[out] INFO */
776 /* > INFO is INTEGER */
777 /* > = 0: successful exit */
778 /* > < 0: if INFO = -i, the i-th argument had an illegal value */
779 /* > > 0: if INFO = i, and i is */
780 /* > <= N: U(i,i) is exactly zero. The factorization */
781 /* > has not been completed unless i = N, but the */
782 /* > factor U is exactly singular, so the solution */
783 /* > and error bounds could not be computed. */
784 /* > RCOND = 0 is returned. */
785 /* > = N+1: U is nonsingular, but RCOND is less than machine */
786 /* > precision, meaning that the matrix is singular */
787 /* > to working precision. Nevertheless, the */
788 /* > solution and error bounds are computed because */
789 /* > there are a number of situations where the */
790 /* > computed solution can be more accurate than the */
791 /* > value of RCOND would suggest. */
797 /* > \author Univ. of Tennessee */
798 /* > \author Univ. of California Berkeley */
799 /* > \author Univ. of Colorado Denver */
800 /* > \author NAG Ltd. */
802 /* > \date December 2016 */
804 /* > \ingroup doubleGTsolve */
806 /* ===================================================================== */
807 /* Subroutine */ int dgtsvx_(char *fact, char *trans, integer *n, integer *
808 nrhs, doublereal *dl, doublereal *d__, doublereal *du, doublereal *
809 dlf, doublereal *df, doublereal *duf, doublereal *du2, integer *ipiv,
810 doublereal *b, integer *ldb, doublereal *x, integer *ldx, doublereal *
811 rcond, doublereal *ferr, doublereal *berr, doublereal *work, integer *
812 iwork, integer *info)
814 /* System generated locals */
815 integer b_dim1, b_offset, x_dim1, x_offset, i__1;
817 /* Local variables */
819 extern logical lsame_(char *, char *);
821 extern /* Subroutine */ int dcopy_(integer *, doublereal *, integer *,
822 doublereal *, integer *);
823 extern doublereal dlamch_(char *), dlangt_(char *, integer *,
824 doublereal *, doublereal *, doublereal *);
826 extern /* Subroutine */ int dlacpy_(char *, integer *, integer *,
827 doublereal *, integer *, doublereal *, integer *),
828 xerbla_(char *, integer *, ftnlen), dgtcon_(char *, integer *,
829 doublereal *, doublereal *, doublereal *, doublereal *, integer *,
830 doublereal *, doublereal *, doublereal *, integer *, integer *), dgtrfs_(char *, integer *, integer *, doublereal *,
831 doublereal *, doublereal *, doublereal *, doublereal *,
832 doublereal *, doublereal *, integer *, doublereal *, integer *,
833 doublereal *, integer *, doublereal *, doublereal *, doublereal *,
834 integer *, integer *), dgttrf_(integer *, doublereal *,
835 doublereal *, doublereal *, doublereal *, integer *, integer *);
837 extern /* Subroutine */ int dgttrs_(char *, integer *, integer *,
838 doublereal *, doublereal *, doublereal *, doublereal *, integer *,
839 doublereal *, integer *, integer *);
842 /* -- LAPACK driver routine (version 3.7.0) -- */
843 /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
844 /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
848 /* ===================================================================== */
851 /* Parameter adjustments */
861 b_offset = 1 + b_dim1 * 1;
864 x_offset = 1 + x_dim1 * 1;
873 nofact = lsame_(fact, "N");
874 notran = lsame_(trans, "N");
875 if (! nofact && ! lsame_(fact, "F")) {
877 } else if (! notran && ! lsame_(trans, "T") && !
878 lsame_(trans, "C")) {
882 } else if (*nrhs < 0) {
884 } else if (*ldb < f2cmax(1,*n)) {
886 } else if (*ldx < f2cmax(1,*n)) {
891 xerbla_("DGTSVX", &i__1, (ftnlen)6);
897 /* Compute the LU factorization of A. */
899 dcopy_(n, &d__[1], &c__1, &df[1], &c__1);
902 dcopy_(&i__1, &dl[1], &c__1, &dlf[1], &c__1);
904 dcopy_(&i__1, &du[1], &c__1, &duf[1], &c__1);
906 dgttrf_(n, &dlf[1], &df[1], &duf[1], &du2[1], &ipiv[1], info);
908 /* Return if INFO is non-zero. */
916 /* Compute the norm of the matrix A. */
919 *(unsigned char *)norm = '1';
921 *(unsigned char *)norm = 'I';
923 anorm = dlangt_(norm, n, &dl[1], &d__[1], &du[1]);
925 /* Compute the reciprocal of the condition number of A. */
927 dgtcon_(norm, n, &dlf[1], &df[1], &duf[1], &du2[1], &ipiv[1], &anorm,
928 rcond, &work[1], &iwork[1], info);
930 /* Compute the solution vectors X. */
932 dlacpy_("Full", n, nrhs, &b[b_offset], ldb, &x[x_offset], ldx);
933 dgttrs_(trans, n, nrhs, &dlf[1], &df[1], &duf[1], &du2[1], &ipiv[1], &x[
934 x_offset], ldx, info);
936 /* Use iterative refinement to improve the computed solutions and */
937 /* compute error bounds and backward error estimates for them. */
939 dgtrfs_(trans, n, nrhs, &dl[1], &d__[1], &du[1], &dlf[1], &df[1], &duf[1],
940 &du2[1], &ipiv[1], &b[b_offset], ldb, &x[x_offset], ldx, &ferr[1]
941 , &berr[1], &work[1], &iwork[1], info);
943 /* Set INFO = N+1 if the matrix is singular to working precision. */
945 if (*rcond < dlamch_("Epsilon")) {