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authorshmel1k <shmel1k@ydb.tech>2022-09-02 12:44:59 +0300
committershmel1k <shmel1k@ydb.tech>2022-09-02 12:44:59 +0300
commit90d450f74722da7859d6f510a869f6c6908fd12f (patch)
tree538c718dedc76cdfe37ad6d01ff250dd930d9278 /contrib/libs/clapack/zptrfs.c
parent01f64c1ecd0d4ffa9e3a74478335f1745f26cc75 (diff)
downloadydb-90d450f74722da7859d6f510a869f6c6908fd12f.tar.gz
[] add metering mode to CLI
Diffstat (limited to 'contrib/libs/clapack/zptrfs.c')
-rw-r--r--contrib/libs/clapack/zptrfs.c576
1 files changed, 576 insertions, 0 deletions
diff --git a/contrib/libs/clapack/zptrfs.c b/contrib/libs/clapack/zptrfs.c
new file mode 100644
index 0000000000..b57ae48d65
--- /dev/null
+++ b/contrib/libs/clapack/zptrfs.c
@@ -0,0 +1,576 @@
+/* zptrfs.f -- translated by f2c (version 20061008).
+ You must link the resulting object file with libf2c:
+ on Microsoft Windows system, link with libf2c.lib;
+ on Linux or Unix systems, link with .../path/to/libf2c.a -lm
+ or, if you install libf2c.a in a standard place, with -lf2c -lm
+ -- in that order, at the end of the command line, as in
+ cc *.o -lf2c -lm
+ Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
+
+ http://www.netlib.org/f2c/libf2c.zip
+*/
+
+#include "f2c.h"
+#include "blaswrap.h"
+
+/* Table of constant values */
+
+static integer c__1 = 1;
+static doublecomplex c_b16 = {1.,0.};
+
+/* Subroutine */ int zptrfs_(char *uplo, integer *n, integer *nrhs,
+ doublereal *d__, doublecomplex *e, doublereal *df, doublecomplex *ef,
+ doublecomplex *b, integer *ldb, doublecomplex *x, integer *ldx,
+ doublereal *ferr, doublereal *berr, doublecomplex *work, doublereal *
+ rwork, integer *info)
+{
+ /* System generated locals */
+ integer b_dim1, b_offset, x_dim1, x_offset, i__1, i__2, i__3, i__4, i__5,
+ i__6;
+ doublereal d__1, d__2, d__3, d__4, d__5, d__6, d__7, d__8, d__9, d__10,
+ d__11, d__12;
+ doublecomplex z__1, z__2, z__3;
+
+ /* Builtin functions */
+ double d_imag(doublecomplex *);
+ void d_cnjg(doublecomplex *, doublecomplex *);
+ double z_abs(doublecomplex *);
+
+ /* Local variables */
+ integer i__, j;
+ doublereal s;
+ doublecomplex bi, cx, dx, ex;
+ integer ix, nz;
+ doublereal eps, safe1, safe2;
+ extern logical lsame_(char *, char *);
+ integer count;
+ logical upper;
+ extern /* Subroutine */ int zaxpy_(integer *, doublecomplex *,
+ doublecomplex *, integer *, doublecomplex *, integer *);
+ extern doublereal dlamch_(char *);
+ extern integer idamax_(integer *, doublereal *, integer *);
+ doublereal safmin;
+ extern /* Subroutine */ int xerbla_(char *, integer *);
+ doublereal lstres;
+ extern /* Subroutine */ int zpttrs_(char *, integer *, integer *,
+ doublereal *, doublecomplex *, doublecomplex *, integer *,
+ integer *);
+
+
+/* -- LAPACK routine (version 3.2) -- */
+/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/* November 2006 */
+
+/* .. Scalar Arguments .. */
+/* .. */
+/* .. Array Arguments .. */
+/* .. */
+
+/* Purpose */
+/* ======= */
+
+/* ZPTRFS improves the computed solution to a system of linear */
+/* equations when the coefficient matrix is Hermitian positive definite */
+/* and tridiagonal, and provides error bounds and backward error */
+/* estimates for the solution. */
+
+/* Arguments */
+/* ========= */
+
+/* UPLO (input) CHARACTER*1 */
+/* Specifies whether the superdiagonal or the subdiagonal of the */
+/* tridiagonal matrix A is stored and the form of the */
+/* factorization: */
+/* = 'U': E is the superdiagonal of A, and A = U**H*D*U; */
+/* = 'L': E is the subdiagonal of A, and A = L*D*L**H. */
+/* (The two forms are equivalent if A is real.) */
+
+/* N (input) INTEGER */
+/* The order of the matrix A. N >= 0. */
+
+/* NRHS (input) INTEGER */
+/* The number of right hand sides, i.e., the number of columns */
+/* of the matrix B. NRHS >= 0. */
+
+/* D (input) DOUBLE PRECISION array, dimension (N) */
+/* The n real diagonal elements of the tridiagonal matrix A. */
+
+/* E (input) COMPLEX*16 array, dimension (N-1) */
+/* The (n-1) off-diagonal elements of the tridiagonal matrix A */
+/* (see UPLO). */
+
+/* DF (input) DOUBLE PRECISION array, dimension (N) */
+/* The n diagonal elements of the diagonal matrix D from */
+/* the factorization computed by ZPTTRF. */
+
+/* EF (input) COMPLEX*16 array, dimension (N-1) */
+/* The (n-1) off-diagonal elements of the unit bidiagonal */
+/* factor U or L from the factorization computed by ZPTTRF */
+/* (see UPLO). */
+
+/* B (input) COMPLEX*16 array, dimension (LDB,NRHS) */
+/* The right hand side matrix B. */
+
+/* LDB (input) INTEGER */
+/* The leading dimension of the array B. LDB >= max(1,N). */
+
+/* X (input/output) COMPLEX*16 array, dimension (LDX,NRHS) */
+/* On entry, the solution matrix X, as computed by ZPTTRS. */
+/* On exit, the improved solution matrix X. */
+
+/* LDX (input) INTEGER */
+/* The leading dimension of the array X. LDX >= max(1,N). */
+
+/* FERR (output) DOUBLE PRECISION array, dimension (NRHS) */
+/* The forward error bound for each solution vector */
+/* X(j) (the j-th column of the solution matrix X). */
+/* If XTRUE is the true solution corresponding to X(j), FERR(j) */
+/* is an estimated upper bound for the magnitude of the largest */
+/* element in (X(j) - XTRUE) divided by the magnitude of the */
+/* largest element in X(j). */
+
+/* BERR (output) DOUBLE PRECISION array, dimension (NRHS) */
+/* The componentwise relative backward error of each solution */
+/* vector X(j) (i.e., the smallest relative change in */
+/* any element of A or B that makes X(j) an exact solution). */
+
+/* WORK (workspace) COMPLEX*16 array, dimension (N) */
+
+/* RWORK (workspace) DOUBLE PRECISION array, dimension (N) */
+
+/* INFO (output) INTEGER */
+/* = 0: successful exit */
+/* < 0: if INFO = -i, the i-th argument had an illegal value */
+
+/* Internal Parameters */
+/* =================== */
+
+/* ITMAX is the maximum number of steps of iterative refinement. */
+
+/* ===================================================================== */
+
+/* .. Parameters .. */
+/* .. */
+/* .. Local Scalars .. */
+/* .. */
+/* .. External Functions .. */
+/* .. */
+/* .. External Subroutines .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+/* .. Statement Functions .. */
+/* .. */
+/* .. Statement Function definitions .. */
+/* .. */
+/* .. Executable Statements .. */
+
+/* Test the input parameters. */
+
+ /* Parameter adjustments */
+ --d__;
+ --e;
+ --df;
+ --ef;
+ b_dim1 = *ldb;
+ b_offset = 1 + b_dim1;
+ b -= b_offset;
+ x_dim1 = *ldx;
+ x_offset = 1 + x_dim1;
+ x -= x_offset;
+ --ferr;
+ --berr;
+ --work;
+ --rwork;
+
+ /* Function Body */
+ *info = 0;
+ upper = lsame_(uplo, "U");
+ if (! upper && ! lsame_(uplo, "L")) {
+ *info = -1;
+ } else if (*n < 0) {
+ *info = -2;
+ } else if (*nrhs < 0) {
+ *info = -3;
+ } else if (*ldb < max(1,*n)) {
+ *info = -9;
+ } else if (*ldx < max(1,*n)) {
+ *info = -11;
+ }
+ if (*info != 0) {
+ i__1 = -(*info);
+ xerbla_("ZPTRFS", &i__1);
+ return 0;
+ }
+
+/* Quick return if possible */
+
+ if (*n == 0 || *nrhs == 0) {
+ i__1 = *nrhs;
+ for (j = 1; j <= i__1; ++j) {
+ ferr[j] = 0.;
+ berr[j] = 0.;
+/* L10: */
+ }
+ return 0;
+ }
+
+/* NZ = maximum number of nonzero elements in each row of A, plus 1 */
+
+ nz = 4;
+ eps = dlamch_("Epsilon");
+ safmin = dlamch_("Safe minimum");
+ safe1 = nz * safmin;
+ safe2 = safe1 / eps;
+
+/* Do for each right hand side */
+
+ i__1 = *nrhs;
+ for (j = 1; j <= i__1; ++j) {
+
+ count = 1;
+ lstres = 3.;
+L20:
+
+/* Loop until stopping criterion is satisfied. */
+
+/* Compute residual R = B - A * X. Also compute */
+/* abs(A)*abs(x) + abs(b) for use in the backward error bound. */
+
+ if (upper) {
+ if (*n == 1) {
+ i__2 = j * b_dim1 + 1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ i__2 = j * x_dim1 + 1;
+ z__1.r = d__[1] * x[i__2].r, z__1.i = d__[1] * x[i__2].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ z__1.r = bi.r - dx.r, z__1.i = bi.i - dx.i;
+ work[1].r = z__1.r, work[1].i = z__1.i;
+ rwork[1] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = dx.r, abs(d__3)) + (d__4 =
+ d_imag(&dx), abs(d__4)));
+ } else {
+ i__2 = j * b_dim1 + 1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ i__2 = j * x_dim1 + 1;
+ z__1.r = d__[1] * x[i__2].r, z__1.i = d__[1] * x[i__2].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ i__2 = j * x_dim1 + 2;
+ z__1.r = e[1].r * x[i__2].r - e[1].i * x[i__2].i, z__1.i = e[
+ 1].r * x[i__2].i + e[1].i * x[i__2].r;
+ ex.r = z__1.r, ex.i = z__1.i;
+ z__2.r = bi.r - dx.r, z__2.i = bi.i - dx.i;
+ z__1.r = z__2.r - ex.r, z__1.i = z__2.i - ex.i;
+ work[1].r = z__1.r, work[1].i = z__1.i;
+ i__2 = j * x_dim1 + 2;
+ rwork[1] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = dx.r, abs(d__3)) + (d__4 =
+ d_imag(&dx), abs(d__4))) + ((d__5 = e[1].r, abs(d__5))
+ + (d__6 = d_imag(&e[1]), abs(d__6))) * ((d__7 = x[
+ i__2].r, abs(d__7)) + (d__8 = d_imag(&x[j * x_dim1 +
+ 2]), abs(d__8)));
+ i__2 = *n - 1;
+ for (i__ = 2; i__ <= i__2; ++i__) {
+ i__3 = i__ + j * b_dim1;
+ bi.r = b[i__3].r, bi.i = b[i__3].i;
+ d_cnjg(&z__2, &e[i__ - 1]);
+ i__3 = i__ - 1 + j * x_dim1;
+ z__1.r = z__2.r * x[i__3].r - z__2.i * x[i__3].i, z__1.i =
+ z__2.r * x[i__3].i + z__2.i * x[i__3].r;
+ cx.r = z__1.r, cx.i = z__1.i;
+ i__3 = i__;
+ i__4 = i__ + j * x_dim1;
+ z__1.r = d__[i__3] * x[i__4].r, z__1.i = d__[i__3] * x[
+ i__4].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ i__3 = i__;
+ i__4 = i__ + 1 + j * x_dim1;
+ z__1.r = e[i__3].r * x[i__4].r - e[i__3].i * x[i__4].i,
+ z__1.i = e[i__3].r * x[i__4].i + e[i__3].i * x[
+ i__4].r;
+ ex.r = z__1.r, ex.i = z__1.i;
+ i__3 = i__;
+ z__3.r = bi.r - cx.r, z__3.i = bi.i - cx.i;
+ z__2.r = z__3.r - dx.r, z__2.i = z__3.i - dx.i;
+ z__1.r = z__2.r - ex.r, z__1.i = z__2.i - ex.i;
+ work[i__3].r = z__1.r, work[i__3].i = z__1.i;
+ i__3 = i__ - 1;
+ i__4 = i__ - 1 + j * x_dim1;
+ i__5 = i__;
+ i__6 = i__ + 1 + j * x_dim1;
+ rwork[i__] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&
+ bi), abs(d__2)) + ((d__3 = e[i__3].r, abs(d__3))
+ + (d__4 = d_imag(&e[i__ - 1]), abs(d__4))) * ((
+ d__5 = x[i__4].r, abs(d__5)) + (d__6 = d_imag(&x[
+ i__ - 1 + j * x_dim1]), abs(d__6))) + ((d__7 =
+ dx.r, abs(d__7)) + (d__8 = d_imag(&dx), abs(d__8))
+ ) + ((d__9 = e[i__5].r, abs(d__9)) + (d__10 =
+ d_imag(&e[i__]), abs(d__10))) * ((d__11 = x[i__6]
+ .r, abs(d__11)) + (d__12 = d_imag(&x[i__ + 1 + j *
+ x_dim1]), abs(d__12)));
+/* L30: */
+ }
+ i__2 = *n + j * b_dim1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ d_cnjg(&z__2, &e[*n - 1]);
+ i__2 = *n - 1 + j * x_dim1;
+ z__1.r = z__2.r * x[i__2].r - z__2.i * x[i__2].i, z__1.i =
+ z__2.r * x[i__2].i + z__2.i * x[i__2].r;
+ cx.r = z__1.r, cx.i = z__1.i;
+ i__2 = *n;
+ i__3 = *n + j * x_dim1;
+ z__1.r = d__[i__2] * x[i__3].r, z__1.i = d__[i__2] * x[i__3]
+ .i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ i__2 = *n;
+ z__2.r = bi.r - cx.r, z__2.i = bi.i - cx.i;
+ z__1.r = z__2.r - dx.r, z__1.i = z__2.i - dx.i;
+ work[i__2].r = z__1.r, work[i__2].i = z__1.i;
+ i__2 = *n - 1;
+ i__3 = *n - 1 + j * x_dim1;
+ rwork[*n] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = e[i__2].r, abs(d__3)) + (d__4 =
+ d_imag(&e[*n - 1]), abs(d__4))) * ((d__5 = x[i__3].r,
+ abs(d__5)) + (d__6 = d_imag(&x[*n - 1 + j * x_dim1]),
+ abs(d__6))) + ((d__7 = dx.r, abs(d__7)) + (d__8 =
+ d_imag(&dx), abs(d__8)));
+ }
+ } else {
+ if (*n == 1) {
+ i__2 = j * b_dim1 + 1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ i__2 = j * x_dim1 + 1;
+ z__1.r = d__[1] * x[i__2].r, z__1.i = d__[1] * x[i__2].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ z__1.r = bi.r - dx.r, z__1.i = bi.i - dx.i;
+ work[1].r = z__1.r, work[1].i = z__1.i;
+ rwork[1] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = dx.r, abs(d__3)) + (d__4 =
+ d_imag(&dx), abs(d__4)));
+ } else {
+ i__2 = j * b_dim1 + 1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ i__2 = j * x_dim1 + 1;
+ z__1.r = d__[1] * x[i__2].r, z__1.i = d__[1] * x[i__2].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ d_cnjg(&z__2, &e[1]);
+ i__2 = j * x_dim1 + 2;
+ z__1.r = z__2.r * x[i__2].r - z__2.i * x[i__2].i, z__1.i =
+ z__2.r * x[i__2].i + z__2.i * x[i__2].r;
+ ex.r = z__1.r, ex.i = z__1.i;
+ z__2.r = bi.r - dx.r, z__2.i = bi.i - dx.i;
+ z__1.r = z__2.r - ex.r, z__1.i = z__2.i - ex.i;
+ work[1].r = z__1.r, work[1].i = z__1.i;
+ i__2 = j * x_dim1 + 2;
+ rwork[1] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = dx.r, abs(d__3)) + (d__4 =
+ d_imag(&dx), abs(d__4))) + ((d__5 = e[1].r, abs(d__5))
+ + (d__6 = d_imag(&e[1]), abs(d__6))) * ((d__7 = x[
+ i__2].r, abs(d__7)) + (d__8 = d_imag(&x[j * x_dim1 +
+ 2]), abs(d__8)));
+ i__2 = *n - 1;
+ for (i__ = 2; i__ <= i__2; ++i__) {
+ i__3 = i__ + j * b_dim1;
+ bi.r = b[i__3].r, bi.i = b[i__3].i;
+ i__3 = i__ - 1;
+ i__4 = i__ - 1 + j * x_dim1;
+ z__1.r = e[i__3].r * x[i__4].r - e[i__3].i * x[i__4].i,
+ z__1.i = e[i__3].r * x[i__4].i + e[i__3].i * x[
+ i__4].r;
+ cx.r = z__1.r, cx.i = z__1.i;
+ i__3 = i__;
+ i__4 = i__ + j * x_dim1;
+ z__1.r = d__[i__3] * x[i__4].r, z__1.i = d__[i__3] * x[
+ i__4].i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ d_cnjg(&z__2, &e[i__]);
+ i__3 = i__ + 1 + j * x_dim1;
+ z__1.r = z__2.r * x[i__3].r - z__2.i * x[i__3].i, z__1.i =
+ z__2.r * x[i__3].i + z__2.i * x[i__3].r;
+ ex.r = z__1.r, ex.i = z__1.i;
+ i__3 = i__;
+ z__3.r = bi.r - cx.r, z__3.i = bi.i - cx.i;
+ z__2.r = z__3.r - dx.r, z__2.i = z__3.i - dx.i;
+ z__1.r = z__2.r - ex.r, z__1.i = z__2.i - ex.i;
+ work[i__3].r = z__1.r, work[i__3].i = z__1.i;
+ i__3 = i__ - 1;
+ i__4 = i__ - 1 + j * x_dim1;
+ i__5 = i__;
+ i__6 = i__ + 1 + j * x_dim1;
+ rwork[i__] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&
+ bi), abs(d__2)) + ((d__3 = e[i__3].r, abs(d__3))
+ + (d__4 = d_imag(&e[i__ - 1]), abs(d__4))) * ((
+ d__5 = x[i__4].r, abs(d__5)) + (d__6 = d_imag(&x[
+ i__ - 1 + j * x_dim1]), abs(d__6))) + ((d__7 =
+ dx.r, abs(d__7)) + (d__8 = d_imag(&dx), abs(d__8))
+ ) + ((d__9 = e[i__5].r, abs(d__9)) + (d__10 =
+ d_imag(&e[i__]), abs(d__10))) * ((d__11 = x[i__6]
+ .r, abs(d__11)) + (d__12 = d_imag(&x[i__ + 1 + j *
+ x_dim1]), abs(d__12)));
+/* L40: */
+ }
+ i__2 = *n + j * b_dim1;
+ bi.r = b[i__2].r, bi.i = b[i__2].i;
+ i__2 = *n - 1;
+ i__3 = *n - 1 + j * x_dim1;
+ z__1.r = e[i__2].r * x[i__3].r - e[i__2].i * x[i__3].i,
+ z__1.i = e[i__2].r * x[i__3].i + e[i__2].i * x[i__3]
+ .r;
+ cx.r = z__1.r, cx.i = z__1.i;
+ i__2 = *n;
+ i__3 = *n + j * x_dim1;
+ z__1.r = d__[i__2] * x[i__3].r, z__1.i = d__[i__2] * x[i__3]
+ .i;
+ dx.r = z__1.r, dx.i = z__1.i;
+ i__2 = *n;
+ z__2.r = bi.r - cx.r, z__2.i = bi.i - cx.i;
+ z__1.r = z__2.r - dx.r, z__1.i = z__2.i - dx.i;
+ work[i__2].r = z__1.r, work[i__2].i = z__1.i;
+ i__2 = *n - 1;
+ i__3 = *n - 1 + j * x_dim1;
+ rwork[*n] = (d__1 = bi.r, abs(d__1)) + (d__2 = d_imag(&bi),
+ abs(d__2)) + ((d__3 = e[i__2].r, abs(d__3)) + (d__4 =
+ d_imag(&e[*n - 1]), abs(d__4))) * ((d__5 = x[i__3].r,
+ abs(d__5)) + (d__6 = d_imag(&x[*n - 1 + j * x_dim1]),
+ abs(d__6))) + ((d__7 = dx.r, abs(d__7)) + (d__8 =
+ d_imag(&dx), abs(d__8)));
+ }
+ }
+
+/* Compute componentwise relative backward error from formula */
+
+/* max(i) ( abs(R(i)) / ( abs(A)*abs(X) + abs(B) )(i) ) */
+
+/* where abs(Z) is the componentwise absolute value of the matrix */
+/* or vector Z. If the i-th component of the denominator is less */
+/* than SAFE2, then SAFE1 is added to the i-th components of the */
+/* numerator and denominator before dividing. */
+
+ s = 0.;
+ i__2 = *n;
+ for (i__ = 1; i__ <= i__2; ++i__) {
+ if (rwork[i__] > safe2) {
+/* Computing MAX */
+ i__3 = i__;
+ d__3 = s, d__4 = ((d__1 = work[i__3].r, abs(d__1)) + (d__2 =
+ d_imag(&work[i__]), abs(d__2))) / rwork[i__];
+ s = max(d__3,d__4);
+ } else {
+/* Computing MAX */
+ i__3 = i__;
+ d__3 = s, d__4 = ((d__1 = work[i__3].r, abs(d__1)) + (d__2 =
+ d_imag(&work[i__]), abs(d__2)) + safe1) / (rwork[i__]
+ + safe1);
+ s = max(d__3,d__4);
+ }
+/* L50: */
+ }
+ berr[j] = s;
+
+/* Test stopping criterion. Continue iterating if */
+/* 1) The residual BERR(J) is larger than machine epsilon, and */
+/* 2) BERR(J) decreased by at least a factor of 2 during the */
+/* last iteration, and */
+/* 3) At most ITMAX iterations tried. */
+
+ if (berr[j] > eps && berr[j] * 2. <= lstres && count <= 5) {
+
+/* Update solution and try again. */
+
+ zpttrs_(uplo, n, &c__1, &df[1], &ef[1], &work[1], n, info);
+ zaxpy_(n, &c_b16, &work[1], &c__1, &x[j * x_dim1 + 1], &c__1);
+ lstres = berr[j];
+ ++count;
+ goto L20;
+ }
+
+/* Bound error from formula */
+
+/* norm(X - XTRUE) / norm(X) .le. FERR = */
+/* norm( abs(inv(A))* */
+/* ( abs(R) + NZ*EPS*( abs(A)*abs(X)+abs(B) ))) / norm(X) */
+
+/* where */
+/* norm(Z) is the magnitude of the largest component of Z */
+/* inv(A) is the inverse of A */
+/* abs(Z) is the componentwise absolute value of the matrix or */
+/* vector Z */
+/* NZ is the maximum number of nonzeros in any row of A, plus 1 */
+/* EPS is machine epsilon */
+
+/* The i-th component of abs(R)+NZ*EPS*(abs(A)*abs(X)+abs(B)) */
+/* is incremented by SAFE1 if the i-th component of */
+/* abs(A)*abs(X) + abs(B) is less than SAFE2. */
+
+ i__2 = *n;
+ for (i__ = 1; i__ <= i__2; ++i__) {
+ if (rwork[i__] > safe2) {
+ i__3 = i__;
+ rwork[i__] = (d__1 = work[i__3].r, abs(d__1)) + (d__2 =
+ d_imag(&work[i__]), abs(d__2)) + nz * eps * rwork[i__]
+ ;
+ } else {
+ i__3 = i__;
+ rwork[i__] = (d__1 = work[i__3].r, abs(d__1)) + (d__2 =
+ d_imag(&work[i__]), abs(d__2)) + nz * eps * rwork[i__]
+ + safe1;
+ }
+/* L60: */
+ }
+ ix = idamax_(n, &rwork[1], &c__1);
+ ferr[j] = rwork[ix];
+
+/* Estimate the norm of inv(A). */
+
+/* Solve M(A) * x = e, where M(A) = (m(i,j)) is given by */
+
+/* m(i,j) = abs(A(i,j)), i = j, */
+/* m(i,j) = -abs(A(i,j)), i .ne. j, */
+
+/* and e = [ 1, 1, ..., 1 ]'. Note M(A) = M(L)*D*M(L)'. */
+
+/* Solve M(L) * x = e. */
+
+ rwork[1] = 1.;
+ i__2 = *n;
+ for (i__ = 2; i__ <= i__2; ++i__) {
+ rwork[i__] = rwork[i__ - 1] * z_abs(&ef[i__ - 1]) + 1.;
+/* L70: */
+ }
+
+/* Solve D * M(L)' * x = b. */
+
+ rwork[*n] /= df[*n];
+ for (i__ = *n - 1; i__ >= 1; --i__) {
+ rwork[i__] = rwork[i__] / df[i__] + rwork[i__ + 1] * z_abs(&ef[
+ i__]);
+/* L80: */
+ }
+
+/* Compute norm(inv(A)) = max(x(i)), 1<=i<=n. */
+
+ ix = idamax_(n, &rwork[1], &c__1);
+ ferr[j] *= (d__1 = rwork[ix], abs(d__1));
+
+/* Normalize error. */
+
+ lstres = 0.;
+ i__2 = *n;
+ for (i__ = 1; i__ <= i__2; ++i__) {
+/* Computing MAX */
+ d__1 = lstres, d__2 = z_abs(&x[i__ + j * x_dim1]);
+ lstres = max(d__1,d__2);
+/* L90: */
+ }
+ if (lstres != 0.) {
+ ferr[j] /= lstres;
+ }
+
+/* L100: */
+ }
+
+ return 0;
+
+/* End of ZPTRFS */
+
+} /* zptrfs_ */