--- /dev/null
+#include "clapack.h"
+
+/* Table of constant values */
+
+static integer c__1 = 1;
+static integer c_n1 = -1;
+static integer c__2 = 2;
+static doublereal c_b18 = 1.;
+static doublereal c_b22 = -1.;
+
+/* Subroutine */ int dtrtri_(char *uplo, char *diag, integer *n, doublereal *
+ a, integer *lda, integer *info)
+{
+ /* System generated locals */
+ address a__1[2];
+ integer a_dim1, a_offset, i__1, i__2[2], i__3, i__4, i__5;
+ char ch__1[2];
+
+ /* Builtin functions */
+ /* Subroutine */ int s_cat(char *, char **, integer *, integer *, ftnlen);
+
+ /* Local variables */
+ integer j, jb, nb, nn;
+ extern logical lsame_(char *, char *);
+ extern /* Subroutine */ int dtrmm_(char *, char *, char *, char *,
+ integer *, integer *, doublereal *, doublereal *, integer *,
+ doublereal *, integer *), dtrsm_(
+ char *, char *, char *, char *, integer *, integer *, doublereal *
+, doublereal *, integer *, doublereal *, integer *);
+ logical upper;
+ extern /* Subroutine */ int dtrti2_(char *, char *, integer *, doublereal
+ *, integer *, integer *), xerbla_(char *, integer
+ *);
+ extern integer ilaenv_(integer *, char *, char *, integer *, integer *,
+ integer *, integer *);
+ logical nounit;
+
+
+/* -- LAPACK routine (version 3.1) -- */
+/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/* November 2006 */
+
+/* .. Scalar Arguments .. */
+/* .. */
+/* .. Array Arguments .. */
+/* .. */
+
+/* Purpose */
+/* ======= */
+
+/* DTRTRI computes the inverse of a real upper or lower triangular */
+/* matrix A. */
+
+/* This is the Level 3 BLAS version of the algorithm. */
+
+/* Arguments */
+/* ========= */
+
+/* UPLO (input) CHARACTER*1 */
+/* = 'U': A is upper triangular; */
+/* = 'L': A is lower triangular. */
+
+/* DIAG (input) CHARACTER*1 */
+/* = 'N': A is non-unit triangular; */
+/* = 'U': A is unit triangular. */
+
+/* N (input) INTEGER */
+/* The order of the matrix A. N >= 0. */
+
+/* A (input/output) DOUBLE PRECISION array, dimension (LDA,N) */
+/* On entry, the triangular matrix A. If UPLO = 'U', the */
+/* leading N-by-N upper triangular part of the array A contains */
+/* the upper triangular matrix, and the strictly lower */
+/* triangular part of A is not referenced. If UPLO = 'L', the */
+/* leading N-by-N lower triangular part of the array A contains */
+/* the lower triangular matrix, and the strictly upper */
+/* triangular part of A is not referenced. If DIAG = 'U', the */
+/* diagonal elements of A are also not referenced and are */
+/* assumed to be 1. */
+/* On exit, the (triangular) inverse of the original matrix, in */
+/* the same storage format. */
+
+/* LDA (input) INTEGER */
+/* The leading dimension of the array A. LDA >= max(1,N). */
+
+/* INFO (output) INTEGER */
+/* = 0: successful exit */
+/* < 0: if INFO = -i, the i-th argument had an illegal value */
+/* > 0: if INFO = i, A(i,i) is exactly zero. The triangular */
+/* matrix is singular and its inverse can not be computed. */
+
+/* ===================================================================== */
+
+/* .. Parameters .. */
+/* .. */
+/* .. Local Scalars .. */
+/* .. */
+/* .. External Functions .. */
+/* .. */
+/* .. External Subroutines .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+/* .. Executable Statements .. */
+
+/* Test the input parameters. */
+
+ /* Parameter adjustments */
+ a_dim1 = *lda;
+ a_offset = 1 + a_dim1;
+ a -= a_offset;
+
+ /* Function Body */
+ *info = 0;
+ upper = lsame_(uplo, "U");
+ nounit = lsame_(diag, "N");
+ if (! upper && ! lsame_(uplo, "L")) {
+ *info = -1;
+ } else if (! nounit && ! lsame_(diag, "U")) {
+ *info = -2;
+ } else if (*n < 0) {
+ *info = -3;
+ } else if (*lda < max(1,*n)) {
+ *info = -5;
+ }
+ if (*info != 0) {
+ i__1 = -(*info);
+ xerbla_("DTRTRI", &i__1);
+ return 0;
+ }
+
+/* Quick return if possible */
+
+ if (*n == 0) {
+ return 0;
+ }
+
+/* Check for singularity if non-unit. */
+
+ if (nounit) {
+ i__1 = *n;
+ for (*info = 1; *info <= i__1; ++(*info)) {
+ if (a[*info + *info * a_dim1] == 0.) {
+ return 0;
+ }
+/* L10: */
+ }
+ *info = 0;
+ }
+
+/* Determine the block size for this environment. */
+
+/* Writing concatenation */
+ i__2[0] = 1, a__1[0] = uplo;
+ i__2[1] = 1, a__1[1] = diag;
+ s_cat(ch__1, a__1, i__2, &c__2, (ftnlen)2);
+ nb = ilaenv_(&c__1, "DTRTRI", ch__1, n, &c_n1, &c_n1, &c_n1);
+ if (nb <= 1 || nb >= *n) {
+
+/* Use unblocked code */
+
+ dtrti2_(uplo, diag, n, &a[a_offset], lda, info);
+ } else {
+
+/* Use blocked code */
+
+ if (upper) {
+
+/* Compute inverse of upper triangular matrix */
+
+ i__1 = *n;
+ i__3 = nb;
+ for (j = 1; i__3 < 0 ? j >= i__1 : j <= i__1; j += i__3) {
+/* Computing MIN */
+ i__4 = nb, i__5 = *n - j + 1;
+ jb = min(i__4,i__5);
+
+/* Compute rows 1:j-1 of current block column */
+
+ i__4 = j - 1;
+ dtrmm_("Left", "Upper", "No transpose", diag, &i__4, &jb, &
+ c_b18, &a[a_offset], lda, &a[j * a_dim1 + 1], lda);
+ i__4 = j - 1;
+ dtrsm_("Right", "Upper", "No transpose", diag, &i__4, &jb, &
+ c_b22, &a[j + j * a_dim1], lda, &a[j * a_dim1 + 1],
+ lda);
+
+/* Compute inverse of current diagonal block */
+
+ dtrti2_("Upper", diag, &jb, &a[j + j * a_dim1], lda, info);
+/* L20: */
+ }
+ } else {
+
+/* Compute inverse of lower triangular matrix */
+
+ nn = (*n - 1) / nb * nb + 1;
+ i__3 = -nb;
+ for (j = nn; i__3 < 0 ? j >= 1 : j <= 1; j += i__3) {
+/* Computing MIN */
+ i__1 = nb, i__4 = *n - j + 1;
+ jb = min(i__1,i__4);
+ if (j + jb <= *n) {
+
+/* Compute rows j+jb:n of current block column */
+
+ i__1 = *n - j - jb + 1;
+ dtrmm_("Left", "Lower", "No transpose", diag, &i__1, &jb,
+ &c_b18, &a[j + jb + (j + jb) * a_dim1], lda, &a[j
+ + jb + j * a_dim1], lda);
+ i__1 = *n - j - jb + 1;
+ dtrsm_("Right", "Lower", "No transpose", diag, &i__1, &jb,
+ &c_b22, &a[j + j * a_dim1], lda, &a[j + jb + j *
+ a_dim1], lda);
+ }
+
+/* Compute inverse of current diagonal block */
+
+ dtrti2_("Lower", diag, &jb, &a[j + j * a_dim1], lda, info);
+/* L30: */
+ }
+ }
+ }
+
+ return 0;
+
+/* End of DTRTRI */
+
+} /* dtrtri_ */
projects / opencv / blobdiff