dtptri (3p)

Name

dtptri - compute the inverse of a real upper or lower triangular matrix A stored in packed format

Synopsis

SUBROUTINE DTPTRI(UPLO, DIAG, N, A, INFO)

CHARACTER*1 UPLO, DIAG
INTEGER N, INFO
DOUBLE PRECISION A(*)

SUBROUTINE DTPTRI_64(UPLO, DIAG, N, A, INFO)

CHARACTER*1 UPLO, DIAG
INTEGER*8 N, INFO
DOUBLE PRECISION A(*)




F95 INTERFACE
SUBROUTINE TPTRI(UPLO, DIAG, N, A, INFO)

CHARACTER(LEN=1) :: UPLO, DIAG
INTEGER :: N, INFO
REAL(8), DIMENSION(:) :: A

SUBROUTINE TPTRI_64(UPLO, DIAG, N, A, INFO)

CHARACTER(LEN=1) :: UPLO, DIAG
INTEGER(8) :: N, INFO
REAL(8), DIMENSION(:) :: A




C INTERFACE
#include <sunperf.h>

void dtptri(char uplo, char diag, int n, double *a, int *info);

void dtptri_64(char uplo, char diag, long n, double *a, long *info);

Description

Oracle Solaris Studio Performance Library                           dtptri(3P)



NAME
       dtptri - compute the inverse of a real upper or lower triangular matrix
       A stored in packed format


SYNOPSIS
       SUBROUTINE DTPTRI(UPLO, DIAG, N, A, INFO)

       CHARACTER*1 UPLO, DIAG
       INTEGER N, INFO
       DOUBLE PRECISION A(*)

       SUBROUTINE DTPTRI_64(UPLO, DIAG, N, A, INFO)

       CHARACTER*1 UPLO, DIAG
       INTEGER*8 N, INFO
       DOUBLE PRECISION A(*)




   F95 INTERFACE
       SUBROUTINE TPTRI(UPLO, DIAG, N, A, INFO)

       CHARACTER(LEN=1) :: UPLO, DIAG
       INTEGER :: N, INFO
       REAL(8), DIMENSION(:) :: A

       SUBROUTINE TPTRI_64(UPLO, DIAG, N, A, INFO)

       CHARACTER(LEN=1) :: UPLO, DIAG
       INTEGER(8) :: N, INFO
       REAL(8), DIMENSION(:) :: A




   C INTERFACE
       #include <sunperf.h>

       void dtptri(char uplo, char diag, int n, double *a, int *info);

       void dtptri_64(char uplo, char diag, long n, double *a, long *info);



PURPOSE
       dtptri computes the inverse of a real upper or lower triangular  matrix
       A stored in packed format.


ARGUMENTS
       UPLO (input)
                 = 'U':  A is upper triangular;
                 = 'L':  A is lower triangular.


       DIAG (input)
                 = 'N':  A is non-unit triangular;
                 = 'U':  A is unit triangular.


       N (input) The order of the matrix A.  N >= 0.


       A (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)
                 On  entry,  the  upper  or  lower triangular matrix A, stored
                 columnwise in a linear array.  The j-th column of A is stored
                 in  the array A as follows: if UPLO = 'U', A(i + (j-1)*j/2) =
                 A(i,j) for 1<=i<=j; if UPLO = 'L', A(i + (j-1)*((2*n-j)/2)  =
                 A(i,j) for j<=i<=n.  See below for further details.  On exit,
                 the (triangular) inverse of the original matrix, in the  same
                 packed storage format.


       INFO (output)
                 = 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.

FURTHER DETAILS
       A triangular matrix A can be transferred to packed storage using one of
       the following program segments:

       UPLO = 'U':                      UPLO = 'L':

             JC = 1                           JC = 1
             DO 2 J = 1, N                    DO 2 J = 1, N
                DO 1 I = 1, J                    DO 1 I = J, N
                   A(JC+I-1) = A(I,J)              A(JC+I-J) = A(I,J)
           1    CONTINUE                    1    CONTINUE
                JC = JC + J                      JC = JC + N - J + 1
           2 CONTINUE                       2 CONTINUE




                                  7 Nov 2015                        dtptri(3P)