comparison ext/clapack/src/dtrti2.c @ 427:905e45637745

Add the CLAPACK and CBLAS/F2C-BLAS files we use

+/* dtrti2.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;
+
+/* Subroutine */ int dtrti2_(char *uplo, char *diag, integer *n, doublereal *
+	a, integer *lda, integer *info)
+{
+    /* System generated locals */
+    integer a_dim1, a_offset, i__1, i__2;
+
+    /* Local variables */
+    integer j;
+    doublereal ajj;
+    extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *, 
+	    integer *);
+    extern logical lsame_(char *, char *);
+    logical upper;
+    extern /* Subroutine */ int dtrmv_(char *, char *, char *, integer *, 
+	    doublereal *, integer *, doublereal *, integer *), xerbla_(char *, integer *);
+    logical nounit;
+
+
+/*  -- LAPACK routine (version 3.2) -- */
+/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/*     November 2006 */
+
+/*     .. Scalar Arguments .. */
+/*     .. */
+/*     .. Array Arguments .. */
+/*     .. */
+
+/*  Purpose */
+/*  ======= */
+
+/*  DTRTI2 computes the inverse of a real upper or lower triangular */
+/*  matrix. */
+
+/*  This is the Level 2 BLAS version of the algorithm. */
+
+/*  Arguments */
+/*  ========= */
+
+/*  UPLO    (input) CHARACTER*1 */
+/*          Specifies whether the matrix A is upper or lower triangular. */
+/*          = 'U':  Upper triangular */
+/*          = 'L':  Lower triangular */
+
+/*  DIAG    (input) CHARACTER*1 */
+/*          Specifies whether or not the matrix A is unit triangular. */
+/*          = 'N':  Non-unit triangular */
+/*          = 'U':  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 = -k, the k-th argument had an illegal value */
+
+/*  ===================================================================== */
+
+/*     .. 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_("DTRTI2", &i__1);
+	return 0;
+    }
+
+    if (upper) {
+
+/*        Compute inverse of upper triangular matrix. */
+
+	i__1 = *n;
+	for (j = 1; j <= i__1; ++j) {
+	    if (nounit) {
+		a[j + j * a_dim1] = 1. / a[j + j * a_dim1];
+		ajj = -a[j + j * a_dim1];
+	    } else {
+		ajj = -1.;
+	    }
+
+/*           Compute elements 1:j-1 of j-th column. */
+
+	    i__2 = j - 1;
+	    dtrmv_("Upper", "No transpose", diag, &i__2, &a[a_offset], lda, &
+		    a[j * a_dim1 + 1], &c__1);
+	    i__2 = j - 1;
+	    dscal_(&i__2, &ajj, &a[j * a_dim1 + 1], &c__1);
+/* L10: */
+	}
+    } else {
+
+/*        Compute inverse of lower triangular matrix. */
+
+	for (j = *n; j >= 1; --j) {
+	    if (nounit) {
+		a[j + j * a_dim1] = 1. / a[j + j * a_dim1];
+		ajj = -a[j + j * a_dim1];
+	    } else {
+		ajj = -1.;
+	    }
+	    if (j < *n) {
+
+/*              Compute elements j+1:n of j-th column. */
+
+		i__1 = *n - j;
+		dtrmv_("Lower", "No transpose", diag, &i__1, &a[j + 1 + (j + 
+			1) * a_dim1], lda, &a[j + 1 + j * a_dim1], &c__1);
+		i__1 = *n - j;
+		dscal_(&i__1, &ajj, &a[j + 1 + j * a_dim1], &c__1);
+	    }
+/* L20: */
+	}
+    }
+
+    return 0;
+
+/*     End of DTRTI2 */
+
+} /* dtrti2_ */