1DPPTRI(1)                LAPACK routine (version 3.1)                DPPTRI(1)
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NAME

6       DPPTRI  -  the  inverse  of a real symmetric positive definite matrix A
7       using the Cholesky factorization A = U**T*U or A = L*L**T  computed  by
8       DPPTRF
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SYNOPSIS

11       SUBROUTINE DPPTRI( UPLO, N, AP, INFO )
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13           CHARACTER      UPLO
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15           INTEGER        INFO, N
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17           DOUBLE         PRECISION AP( * )
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PURPOSE

20       DPPTRI  computes  the  inverse  of  a  real symmetric positive definite
21       matrix A using the Cholesky factorization A = U**T*U or A = L*L**T com‐
22       puted by DPPTRF.
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ARGUMENTS

26       UPLO    (input) CHARACTER*1
27               = 'U':  Upper triangular factor is stored in AP;
28               = 'L':  Lower triangular factor is stored in AP.
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30       N       (input) INTEGER
31               The order of the matrix A.  N >= 0.
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33       AP      (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)
34               On  entry,  the triangular factor U or L from the Cholesky fac‐
35               torization A = U**T*U or A = L*L**T,  packed  columnwise  as  a
36               linear array.  The j-th column of U or L is stored in the array
37               AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2)  =  U(i,j)  for
38               1<=i<=j;  if  UPLO  =  'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for
39               j<=i<=n.
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41               On exit, the upper or lower triangle of the (symmetric) inverse
42               of A, overwriting the input factor U or L.
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44       INFO    (output) INTEGER
45               = 0:  successful exit
46               < 0:  if INFO = -i, the i-th argument had an illegal value
47               >  0:   if  INFO = i, the (i,i) element of the factor U or L is
48               zero, and the inverse could not be computed.
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52 LAPACK routine (version 3.1)    November 2006                       DPPTRI(1)
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