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

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

10       SUBROUTINE ZHEGST( 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       ZHEGST 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**H)*A*inv(U) or inv(L)*A*inv(L**H)
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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**H or L**H*A*L.
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28       B must have been previously factorized as U**H*U or L*L**H by ZPOTRF.
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ARGUMENTS

32       ITYPE   (input) INTEGER
33               = 1: compute inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H);
34               = 2 or 3: compute U*A*U**H or L**H*A*L.
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36       UPLO    (input) CHARACTER*1
37               =  'U':   Upper  triangle  of  A is stored and B is factored as
38               U**H*U; = 'L':  Lower triangle of A is stored and B is factored
39               as L*L**H.
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41       N       (input) INTEGER
42               The order of the matrices A and B.  N >= 0.
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44       A       (input/output) COMPLEX*16 array, dimension (LDA,N)
45               On  entry,  the Hermitian matrix A.  If UPLO = 'U', the leading
46               N-by-N upper triangular part of A contains the upper triangular
47               part of the matrix A, and the strictly lower triangular part of
48               A is not referenced.  If UPLO = 'L', the leading  N-by-N  lower
49               triangular  part of A contains the lower triangular part of the
50               matrix A, and the strictly upper triangular part of  A  is  not
51               referenced.
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53               On  exit,  if  INFO  = 0, the transformed matrix, stored in the
54               same format as A.
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56       LDA     (input) INTEGER
57               The leading dimension of the array A.  LDA >= max(1,N).
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59       B       (input) COMPLEX*16 array, dimension (LDB,N)
60               The triangular factor from the Cholesky factorization of B,  as
61               returned by ZPOTRF.
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63       LDB     (input) INTEGER
64               The leading dimension of the array B.  LDB >= max(1,N).
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66       INFO    (output) INTEGER
67               = 0:  successful exit
68               < 0:  if INFO = -i, the i-th argument had an illegal value
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72 LAPACK routine (version 3.1)    November 2006                       ZHEGST(1)
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