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diff libcruft/lapack/ctrti2.f @ 7789:82be108cc558

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First attempt at single precision tyeps * * * corrections to qrupdate single precision routines * * * prefer demotion to single over promotion to double * * * Add single precision support to log2 function * * * Trivial PROJECT file update * * * Cache optimized hermitian/transpose methods * * * Add tests for tranpose/hermitian and ChangeLog entry for new transpose code
author David Bateman <dbateman@free.fr>
date Sun, 27 Apr 2008 22:34:17 +0200
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcruft/lapack/ctrti2.f	Sun Apr 27 22:34:17 2008 +0200
@@ -0,0 +1,146 @@
+      SUBROUTINE CTRTI2( UPLO, DIAG, N, A, LDA, INFO )
+*
+*  -- LAPACK routine (version 3.1) --
+*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
+*     November 2006
+*
+*     .. Scalar Arguments ..
+      CHARACTER          DIAG, UPLO
+      INTEGER            INFO, LDA, N
+*     ..
+*     .. Array Arguments ..
+      COMPLEX            A( LDA, * )
+*     ..
+*
+*  Purpose
+*  =======
+*
+*  CTRTI2 computes the inverse of a complex 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) COMPLEX 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 ..
+      COMPLEX            ONE
+      PARAMETER          ( ONE = ( 1.0E+0, 0.0E+0 ) )
+*     ..
+*     .. Local Scalars ..
+      LOGICAL            NOUNIT, UPPER
+      INTEGER            J
+      COMPLEX            AJJ
+*     ..
+*     .. External Functions ..
+      LOGICAL            LSAME
+      EXTERNAL           LSAME
+*     ..
+*     .. External Subroutines ..
+      EXTERNAL           CSCAL, CTRMV, XERBLA
+*     ..
+*     .. Intrinsic Functions ..
+      INTRINSIC          MAX
+*     ..
+*     .. Executable Statements ..
+*
+*     Test the input parameters.
+*
+      INFO = 0
+      UPPER = LSAME( UPLO, 'U' )
+      NOUNIT = LSAME( DIAG, 'N' )
+      IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
+         INFO = -1
+      ELSE IF( .NOT.NOUNIT .AND. .NOT.LSAME( DIAG, 'U' ) ) THEN
+         INFO = -2
+      ELSE IF( N.LT.0 ) THEN
+         INFO = -3
+      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
+         INFO = -5
+      END IF
+      IF( INFO.NE.0 ) THEN
+         CALL XERBLA( 'CTRTI2', -INFO )
+         RETURN
+      END IF
+*
+      IF( UPPER ) THEN
+*
+*        Compute inverse of upper triangular matrix.
+*
+         DO 10 J = 1, N
+            IF( NOUNIT ) THEN
+               A( J, J ) = ONE / A( J, J )
+               AJJ = -A( J, J )
+            ELSE
+               AJJ = -ONE
+            END IF
+*
+*           Compute elements 1:j-1 of j-th column.
+*
+            CALL CTRMV( 'Upper', 'No transpose', DIAG, J-1, A, LDA,
+     $                  A( 1, J ), 1 )
+            CALL CSCAL( J-1, AJJ, A( 1, J ), 1 )
+   10    CONTINUE
+      ELSE
+*
+*        Compute inverse of lower triangular matrix.
+*
+         DO 20 J = N, 1, -1
+            IF( NOUNIT ) THEN
+               A( J, J ) = ONE / A( J, J )
+               AJJ = -A( J, J )
+            ELSE
+               AJJ = -ONE
+            END IF
+            IF( J.LT.N ) THEN
+*
+*              Compute elements j+1:n of j-th column.
+*
+               CALL CTRMV( 'Lower', 'No transpose', DIAG, N-J,
+     $                     A( J+1, J+1 ), LDA, A( J+1, J ), 1 )
+               CALL CSCAL( N-J, AJJ, A( J+1, J ), 1 )
+            END IF
+   20    CONTINUE
+      END IF
+*
+      RETURN
+*
+*     End of CTRTI2
+*
+      END