Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     dpotri - compute the inverse of a  real  symmetric  positive
     definite  matrix  A  using  the  Cholesky  factorization A =
     U**T*U or A = L*L**T computed by DPOTRF

SYNOPSIS

     SUBROUTINE DPOTRI(UPLO, N, A, LDA, INFO)

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

     SUBROUTINE DPOTRI_64(UPLO, N, A, LDA, INFO)

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

  F95 INTERFACE
     SUBROUTINE POTRI(UPLO, [N], A, [LDA], [INFO])

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

     SUBROUTINE POTRI_64(UPLO, [N], A, [LDA], [INFO])

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

  C INTERFACE
     #include <sunperf.h>

     void dpotri(char uplo,  int  n,  double  *a,  int  lda,  int
               *info);

     void dpotri_64(char uplo, long n, double *a, long lda,  long
               *info);

PURPOSE

     dpotri computes the inverse of  a  real  symmetric  positive
     definite  matrix  A  using  the  Cholesky  factorization A =
     U**T*U or A = L*L**T computed by DPOTRF.

ARGUMENTS

     UPLO (input)
               = 'U':  Upper triangle of A is stored;
               = 'L':  Lower triangle of A is stored.

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

     A (input/output)
               On entry, the triangular factor U or  L  from  the
               Cholesky  factorization  A = U**T*U or A = L*L**T,
               as computed by DPOTRF.   On  exit,  the  upper  or
               lower  triangle  of  the (symmetric) inverse of A,
               overwriting the input factor U or L.

     LDA (input)
               The leading dimension of  the  array  A.   LDA  >=
               max(1,N).

     INFO (output)
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille-
               gal value
               > 0:  if INFO = i, the (i,i) element of the factor
               U  or L is zero, and the inverse could not be com-
               puted.