1ZHEGS2(1)                LAPACK routine (version 3.1)                ZHEGS2(1)
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NAME

6       ZHEGS2 - a complex Hermitian-definite generalized eigenproblem to stan‐
7       dard form
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SYNOPSIS

10       SUBROUTINE ZHEGS2( 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           COMPLEX*16     A( LDA, * ), B( LDB, * )
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PURPOSE

19       ZHEGS2 reduces a complex Hermitian-definite generalized eigenproblem to
20       standard form.
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22       If ITYPE = 1, the problem is A*x = lambda*B*x,
23       and A is overwritten by inv(U')*A*inv(U) or inv(L)*A*inv(L')
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25       If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or
26       B*A*x = lambda*x, and A is overwritten by U*A*U` or L'*A*L.
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28       B must have been previously factorized as U'*U or L*L' by ZPOTRF.
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ARGUMENTS

32       ITYPE   (input) INTEGER
33               = 1: compute inv(U')*A*inv(U) or inv(L)*A*inv(L');
34               = 2 or 3: compute U*A*U' or L'*A*L.
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36       UPLO    (input) CHARACTER*1
37               Specifies  whether  the  upper  or lower triangular part of the
38               Hermitian matrix A is stored, and how B has been factorized.  =
39               'U':  Upper triangular
40               = 'L':  Lower triangular
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42       N       (input) INTEGER
43               The order of the matrices A and B.  N >= 0.
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45       A       (input/output) COMPLEX*16 array, dimension (LDA,N)
46               On entry, the Hermitian matrix A.  If UPLO = 'U', the leading n
47               by n upper triangular part of A contains the  upper  triangular
48               part of the matrix A, and the strictly lower triangular part of
49               A is not referenced.  If UPLO = 'L', the leading n by  n  lower
50               triangular  part of A contains the lower triangular part of the
51               matrix A, and the strictly upper triangular part of  A  is  not
52               referenced.
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54               On  exit,  if  INFO  = 0, the transformed matrix, stored in the
55               same format as A.
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57       LDA     (input) INTEGER
58               The leading dimension of the array A.  LDA >= max(1,N).
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60       B       (input) COMPLEX*16 array, dimension (LDB,N)
61               The triangular factor from the Cholesky factorization of B,  as
62               returned by ZPOTRF.
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64       LDB     (input) INTEGER
65               The leading dimension of the array B.  LDB >= max(1,N).
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67       INFO    (output) INTEGER
68               = 0:  successful exit.
69               < 0:  if INFO = -i, the i-th argument had an illegal value.
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73 LAPACK routine (version 3.1)    November 2006                       ZHEGS2(1)
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