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

6       SSPGST  - reduces a real symmetric-definite generalized eigenproblem to
7       standard form, using packed storage
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SYNOPSIS

10       SUBROUTINE SSPGST( ITYPE, UPLO, N, AP, BP, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, ITYPE, N
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16           REAL           AP( * ), BP( * )
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PURPOSE

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

28       ITYPE   (input) INTEGER
29               = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T);
30               = 2 or 3: compute U*A*U**T or L**T*A*L.
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32       UPLO    (input) CHARACTER*1
33               = 'U':  Upper triangle of A is stored  and  B  is  factored  as
34               U**T*U; = 'L':  Lower triangle of A is stored and B is factored
35               as L*L**T.
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37       N       (input) INTEGER
38               The order of the matrices A and B.  N >= 0.
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40       AP      (input/output) REAL array, dimension (N*(N+1)/2)
41               On entry, the upper or lower triangle of the  symmetric  matrix
42               A,  packed  columnwise in a linear array.  The j-th column of A
43               is stored in the array AP as follows: if UPLO  =  'U',  AP(i  +
44               (j-1)*j/2)  =  A(i,j)  for  1<=i<=j;  if  UPLO  =  'L',  AP(i +
45               (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.  On exit, if  INFO  =  0,
46               the transformed matrix, stored in the same format as A.
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48       BP      (input) REAL array, dimension (N*(N+1)/2)
49               The  triangular  factor  from  the Cholesky factorization of B,
50               stored in the same format as A, as returned by SPPTRF.
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52       INFO    (output) INTEGER
53               = 0:  successful exit
54               < 0:  if INFO = -i, the i-th argument had an illegal value
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58 LAPACK routine (version 3.2)    November 2008                       SSPGST(1)
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