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241 lines
6.7 KiB
241 lines
6.7 KiB
/* strtri.f -- translated by f2c (version 20061008). |
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You must link the resulting object file with libf2c: |
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on Microsoft Windows system, link with libf2c.lib; |
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm |
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or, if you install libf2c.a in a standard place, with -lf2c -lm |
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-- in that order, at the end of the command line, as in |
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cc *.o -lf2c -lm |
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., |
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http://www.netlib.org/f2c/libf2c.zip |
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*/ |
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#include "clapack.h" |
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/* Table of constant values */ |
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static integer c__1 = 1; |
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static integer c_n1 = -1; |
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static integer c__2 = 2; |
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static real c_b18 = 1.f; |
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static real c_b22 = -1.f; |
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/* Subroutine */ int strtri_(char *uplo, char *diag, integer *n, real *a, |
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integer *lda, integer *info) |
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{ |
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/* System generated locals */ |
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address a__1[2]; |
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integer a_dim1, a_offset, i__1, i__2[2], i__3, i__4, i__5; |
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char ch__1[2]; |
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/* Builtin functions */ |
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/* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen); |
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/* Local variables */ |
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integer j, jb, nb, nn; |
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extern logical lsame_(char *, char *); |
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logical upper; |
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extern /* Subroutine */ int strmm_(char *, char *, char *, char *, |
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integer *, integer *, real *, real *, integer *, real *, integer * |
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), strsm_(char *, char *, char *, |
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char *, integer *, integer *, real *, real *, integer *, real *, |
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integer *), strti2_(char *, char * |
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, integer *, real *, integer *, integer *), |
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xerbla_(char *, integer *); |
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extern integer ilaenv_(integer *, char *, char *, integer *, integer *, |
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integer *, integer *); |
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logical nounit; |
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/* -- LAPACK routine (version 3.2) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* STRTRI computes the inverse of a real upper or lower triangular */ |
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/* matrix A. */ |
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/* This is the Level 3 BLAS version of the algorithm. */ |
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/* Arguments */ |
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/* ========= */ |
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/* UPLO (input) CHARACTER*1 */ |
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/* = 'U': A is upper triangular; */ |
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/* = 'L': A is lower triangular. */ |
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/* DIAG (input) CHARACTER*1 */ |
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/* = 'N': A is non-unit triangular; */ |
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/* = 'U': A is unit triangular. */ |
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/* N (input) INTEGER */ |
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/* The order of the matrix A. N >= 0. */ |
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/* A (input/output) REAL array, dimension (LDA,N) */ |
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/* On entry, the triangular matrix A. If UPLO = 'U', the */ |
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/* leading N-by-N upper triangular part of the array A contains */ |
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/* the upper triangular matrix, and the strictly lower */ |
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/* triangular part of A is not referenced. If UPLO = 'L', the */ |
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/* leading N-by-N lower triangular part of the array A contains */ |
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/* the lower triangular matrix, and the strictly upper */ |
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/* triangular part of A is not referenced. If DIAG = 'U', the */ |
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/* diagonal elements of A are also not referenced and are */ |
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/* assumed to be 1. */ |
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/* On exit, the (triangular) inverse of the original matrix, in */ |
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/* the same storage format. */ |
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/* LDA (input) INTEGER */ |
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/* The leading dimension of the array A. LDA >= max(1,N). */ |
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/* INFO (output) INTEGER */ |
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/* = 0: successful exit */ |
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/* < 0: if INFO = -i, the i-th argument had an illegal value */ |
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/* > 0: if INFO = i, A(i,i) is exactly zero. The triangular */ |
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/* matrix is singular and its inverse can not be computed. */ |
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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Test the input parameters. */ |
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/* Parameter adjustments */ |
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a_dim1 = *lda; |
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a_offset = 1 + a_dim1; |
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a -= a_offset; |
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/* Function Body */ |
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*info = 0; |
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upper = lsame_(uplo, "U"); |
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nounit = lsame_(diag, "N"); |
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if (! upper && ! lsame_(uplo, "L")) { |
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*info = -1; |
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} else if (! nounit && ! lsame_(diag, "U")) { |
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*info = -2; |
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} else if (*n < 0) { |
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*info = -3; |
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} else if (*lda < max(1,*n)) { |
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*info = -5; |
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} |
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if (*info != 0) { |
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i__1 = -(*info); |
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xerbla_("STRTRI", &i__1); |
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return 0; |
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} |
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/* Quick return if possible */ |
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if (*n == 0) { |
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return 0; |
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} |
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/* Check for singularity if non-unit. */ |
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if (nounit) { |
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i__1 = *n; |
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for (*info = 1; *info <= i__1; ++(*info)) { |
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if (a[*info + *info * a_dim1] == 0.f) { |
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return 0; |
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} |
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/* L10: */ |
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} |
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*info = 0; |
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} |
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/* Determine the block size for this environment. */ |
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/* Writing concatenation */ |
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i__2[0] = 1, a__1[0] = uplo; |
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i__2[1] = 1, a__1[1] = diag; |
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s_cat(ch__1, a__1, i__2, &c__2, (ftnlen)2); |
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nb = ilaenv_(&c__1, "STRTRI", ch__1, n, &c_n1, &c_n1, &c_n1); |
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if (nb <= 1 || nb >= *n) { |
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/* Use unblocked code */ |
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strti2_(uplo, diag, n, &a[a_offset], lda, info); |
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} else { |
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/* Use blocked code */ |
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if (upper) { |
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/* Compute inverse of upper triangular matrix */ |
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i__1 = *n; |
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i__3 = nb; |
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for (j = 1; i__3 < 0 ? j >= i__1 : j <= i__1; j += i__3) { |
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/* Computing MIN */ |
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i__4 = nb, i__5 = *n - j + 1; |
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jb = min(i__4,i__5); |
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/* Compute rows 1:j-1 of current block column */ |
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i__4 = j - 1; |
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strmm_("Left", "Upper", "No transpose", diag, &i__4, &jb, & |
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c_b18, &a[a_offset], lda, &a[j * a_dim1 + 1], lda); |
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i__4 = j - 1; |
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strsm_("Right", "Upper", "No transpose", diag, &i__4, &jb, & |
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c_b22, &a[j + j * a_dim1], lda, &a[j * a_dim1 + 1], |
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lda); |
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/* Compute inverse of current diagonal block */ |
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strti2_("Upper", diag, &jb, &a[j + j * a_dim1], lda, info); |
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/* L20: */ |
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} |
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} else { |
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/* Compute inverse of lower triangular matrix */ |
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nn = (*n - 1) / nb * nb + 1; |
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i__3 = -nb; |
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for (j = nn; i__3 < 0 ? j >= 1 : j <= 1; j += i__3) { |
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/* Computing MIN */ |
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i__1 = nb, i__4 = *n - j + 1; |
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jb = min(i__1,i__4); |
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if (j + jb <= *n) { |
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/* Compute rows j+jb:n of current block column */ |
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i__1 = *n - j - jb + 1; |
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strmm_("Left", "Lower", "No transpose", diag, &i__1, &jb, |
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&c_b18, &a[j + jb + (j + jb) * a_dim1], lda, &a[j |
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+ jb + j * a_dim1], lda); |
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i__1 = *n - j - jb + 1; |
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strsm_("Right", "Lower", "No transpose", diag, &i__1, &jb, |
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&c_b22, &a[j + j * a_dim1], lda, &a[j + jb + j * |
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a_dim1], lda); |
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} |
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/* Compute inverse of current diagonal block */ |
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strti2_("Lower", diag, &jb, &a[j + j * a_dim1], lda, info); |
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/* L30: */ |
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} |
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} |
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} |
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return 0; |
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/* End of STRTRI */ |
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} /* strtri_ */
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