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

6       SSYGST  - reduces a real symmetric-definite generalized eigenproblem to
7       standard form
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SYNOPSIS

10       SUBROUTINE SSYGST( ITYPE, UPLO, N, A, LDA, B, LDB, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, ITYPE, LDA, LDB, N
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16           REAL           A( LDA, * ), B( LDB, * )
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PURPOSE

19       SSYGST reduces a real symmetric-definite  generalized  eigenproblem  to
20       standard form.  If ITYPE = 1, the problem is A*x = lambda*B*x,
21       and  A  is  overwritten  by inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T) If
22       ITYPE = 2 or 3, the problem is A*B*x = lambda*x or
23       B*A*x = lambda*x, and A is overwritten by U*A*U**T or L**T*A*L.  B must
24       have been previously factorized as U**T*U or L*L**T by SPOTRF.
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ARGUMENTS

27       ITYPE   (input) INTEGER
28               = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T);
29               = 2 or 3: compute U*A*U**T or L**T*A*L.
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31       UPLO    (input) CHARACTER*1
32               =  'U':   Upper  triangle  of  A is stored and B is factored as
33               U**T*U; = 'L':  Lower triangle of A is stored and B is factored
34               as L*L**T.
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36       N       (input) INTEGER
37               The order of the matrices A and B.  N >= 0.
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39       A       (input/output) REAL array, dimension (LDA,N)
40               On  entry,  the symmetric matrix A.  If UPLO = 'U', the leading
41               N-by-N upper triangular part of A contains the upper triangular
42               part of the matrix A, and the strictly lower triangular part of
43               A is not referenced.  If UPLO = 'L', the leading  N-by-N  lower
44               triangular  part of A contains the lower triangular part of the
45               matrix A, and the strictly upper triangular part of  A  is  not
46               referenced.   On  exit,  if  INFO  = 0, the transformed matrix,
47               stored in the same format as A.
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49       LDA     (input) INTEGER
50               The leading dimension of the array A.  LDA >= max(1,N).
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52       B       (input) REAL array, dimension (LDB,N)
53               The triangular factor from the Cholesky factorization of B,  as
54               returned by SPOTRF.
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56       LDB     (input) INTEGER
57               The leading dimension of the array B.  LDB >= max(1,N).
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59       INFO    (output) INTEGER
60               = 0:  successful exit
61               < 0:  if INFO = -i, the i-th argument had an illegal value
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65 LAPACK routine (version 3.2)    November 2008                       SSYGST(1)
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