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

6       SGEBAK  -  the  right  or left eigenvectors of a real general matrix by
7       backward transformation on the computed eigenvectors  of  the  balanced
8       matrix output by SGEBAL
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SYNOPSIS

11       SUBROUTINE SGEBAK( JOB, SIDE, N, ILO, IHI, SCALE, M, V, LDV, INFO )
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13           CHARACTER      JOB, SIDE
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15           INTEGER        IHI, ILO, INFO, LDV, M, N
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17           REAL           V( LDV, * ), SCALE( * )
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PURPOSE

20       SGEBAK forms the right or left eigenvectors of a real general matrix by
21       backward transformation on the computed eigenvectors  of  the  balanced
22       matrix output by SGEBAL.
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ARGUMENTS

26       JOB     (input) CHARACTER*1
27               Specifies  the type of backward transformation required: = 'N',
28               do nothing, return immediately; = 'P', do backward  transforma‐
29               tion  for  permutation  only; = 'S', do backward transformation
30               for scaling only; = 'B', do backward transformations  for  both
31               permutation  and scaling.  JOB must be the same as the argument
32               JOB supplied to SGEBAL.
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34       SIDE    (input) CHARACTER*1
35               = 'R':  V contains right eigenvectors;
36               = 'L':  V contains left eigenvectors.
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38       N       (input) INTEGER
39               The number of rows of the matrix V.  N >= 0.
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41       ILO     (input) INTEGER
42               IHI     (input) INTEGER The integers ILO and IHI determined  by
43               SGEBAL.   1  <=  ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if
44               N=0.
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46       SCALE   (input) REAL array, dimension (N)
47               Details of the permutation and scaling factors, as returned  by
48               SGEBAL.
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50       M       (input) INTEGER
51               The number of columns of the matrix V.  M >= 0.
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53       V       (input/output) REAL array, dimension (LDV,M)
54               On entry, the matrix of right or left eigenvectors to be trans‐
55               formed, as returned by SHSEIN or STREVC.  On exit, V  is  over‐
56               written by the transformed eigenvectors.
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58       LDV     (input) INTEGER
59               The leading dimension of the array V. LDV >= max(1,N).
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61       INFO    (output) INTEGER
62               = 0:  successful exit
63               < 0:  if INFO = -i, the i-th argument had an illegal value.
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67 LAPACK routine (version 3.1)    November 2006                       SGEBAK(1)
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