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183 lines
5.0 KiB
183 lines
5.0 KiB
/* dtrti2.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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/* Subroutine */ int dtrti2_(char *uplo, char *diag, integer *n, doublereal * |
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a, integer *lda, integer *info) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, i__1, i__2; |
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/* Local variables */ |
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integer j; |
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doublereal ajj; |
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extern /* Subroutine */ int dscal_(integer *, doublereal *, doublereal *, |
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integer *); |
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extern logical lsame_(char *, char *); |
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logical upper; |
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extern /* Subroutine */ int dtrmv_(char *, char *, char *, integer *, |
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doublereal *, integer *, doublereal *, integer *), xerbla_(char *, 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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/* DTRTI2 computes the inverse of a real upper or lower triangular */ |
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/* matrix. */ |
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/* This is the Level 2 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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/* Specifies whether the matrix A is upper or lower triangular. */ |
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/* = 'U': Upper triangular */ |
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/* = 'L': Lower triangular */ |
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/* DIAG (input) CHARACTER*1 */ |
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/* Specifies whether or not the matrix A is unit triangular. */ |
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/* = 'N': Non-unit triangular */ |
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/* = 'U': 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) DOUBLE PRECISION 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 = -k, the k-th argument had an illegal value */ |
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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_("DTRTI2", &i__1); |
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return 0; |
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} |
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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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for (j = 1; j <= i__1; ++j) { |
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if (nounit) { |
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a[j + j * a_dim1] = 1. / a[j + j * a_dim1]; |
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ajj = -a[j + j * a_dim1]; |
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} else { |
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ajj = -1.; |
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} |
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/* Compute elements 1:j-1 of j-th column. */ |
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i__2 = j - 1; |
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dtrmv_("Upper", "No transpose", diag, &i__2, &a[a_offset], lda, & |
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a[j * a_dim1 + 1], &c__1); |
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i__2 = j - 1; |
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dscal_(&i__2, &ajj, &a[j * a_dim1 + 1], &c__1); |
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/* L10: */ |
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} |
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} else { |
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/* Compute inverse of lower triangular matrix. */ |
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for (j = *n; j >= 1; --j) { |
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if (nounit) { |
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a[j + j * a_dim1] = 1. / a[j + j * a_dim1]; |
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ajj = -a[j + j * a_dim1]; |
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} else { |
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ajj = -1.; |
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} |
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if (j < *n) { |
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/* Compute elements j+1:n of j-th column. */ |
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i__1 = *n - j; |
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dtrmv_("Lower", "No transpose", diag, &i__1, &a[j + 1 + (j + |
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1) * a_dim1], lda, &a[j + 1 + j * a_dim1], &c__1); |
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i__1 = *n - j; |
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dscal_(&i__1, &ajj, &a[j + 1 + j * a_dim1], &c__1); |
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} |
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/* L20: */ |
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} |
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} |
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return 0; |
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/* End of DTRTI2 */ |
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} /* dtrti2_ */
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