1SPOTRF(1)                LAPACK routine (version 3.2)                SPOTRF(1)
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NAME

6       SPOTRF  - computes the Cholesky factorization of a real symmetric posi‐
7       tive definite matrix A
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SYNOPSIS

10       SUBROUTINE SPOTRF( UPLO, N, A, LDA, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, LDA, N
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16           REAL           A( LDA, * )
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PURPOSE

19       SPOTRF computes the Cholesky factorization of a real symmetric positive
20       definite matrix A.  The factorization has the form
21          A = U**T * U,  if UPLO = 'U', or
22          A = L  * L**T,  if UPLO = 'L',
23       where  U is an upper triangular matrix and L is lower triangular.  This
24       is the block version of the algorithm, calling Level 3 BLAS.
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ARGUMENTS

27       UPLO    (input) CHARACTER*1
28               = 'U':  Upper triangle of A is stored;
29               = 'L':  Lower triangle of A is stored.
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31       N       (input) INTEGER
32               The order of the matrix A.  N >= 0.
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34       A       (input/output) REAL array, dimension (LDA,N)
35               On entry, the symmetric matrix A.  If UPLO = 'U',  the  leading
36               N-by-N upper triangular part of A contains the upper triangular
37               part of the matrix A, and the strictly lower triangular part of
38               A  is  not referenced.  If UPLO = 'L', the leading N-by-N lower
39               triangular part of A contains the lower triangular part of  the
40               matrix  A,  and  the strictly upper triangular part of A is not
41               referenced.  On exit, if INFO = 0, the factor U or L  from  the
42               Cholesky factorization A = U**T*U or A = L*L**T.
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44       LDA     (input) INTEGER
45               The leading dimension of the array A.  LDA >= max(1,N).
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47       INFO    (output) INTEGER
48               = 0:  successful exit
49               < 0:  if INFO = -i, the i-th argument had an illegal value
50               > 0:  if INFO = i, the leading minor of order i is not positive
51               definite, and the factorization could not be completed.
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55 LAPACK routine (version 3.2)    November 2008                       SPOTRF(1)
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