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NAME
     chpco - compute the UDU factorization and  condition  number
     of a Hermitian matrix A in packed storage.  If the condition
     number is not needed then xHPFA is slightly faster.   It  is
     typical  to  follow  a call to xHPCO with a call to xHPSL to
     solve Ax =  b  or  to  xHPDI  to  compute  the  determinant,
     inverse, and inertia of A.

SYNOPSIS
     SUBROUTINE ZHPCO (ZA, N, IPIVOT, DRCOND, ZWORK)

     SUBROUTINE CHPCO (CA, N, IPIVOT, SRCOND, CWORK)



     #include <sunperf.h>

     void zhpco(doublecomplex *za, int  n,  int  *ipivit,  double
               *rcond)

     void chpco(complex *ca, int n, int *ipivit, float *rcond) ;

ARGUMENTS
     xA        On entry, the upper triangle of the matrix A.   On
               exit, a UDU factorization of the matrix A.

     N         Order of the matrix A.  N >= 0.

     IPIVOT    On exit, a vector of pivot indices.

     xRCOND    On exit, an estimate of the  reciprocal  condition
               number  of  A.  0.0 <= RCOND <= 1.0.  As the value
               of RCOND gets smaller, operations with A  such  as
               solving  Ax  = b may become less stable.  If RCOND
               satisfies RCOND + 1.0 = 1.0 then A may be singular
               to working precision.

     xWORK     Scratch array with a dimension of N.

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER    LENGTA, N
           PARAMETER (N = 3)
           PARAMETER (LENGTA = (N * N + N) / 2)
     C
           REAL       RCOND
           COMPLEX    A(LENGTA), B(N), WORK(N)
           INTEGER    IPIVOT(N)
     C
           EXTERNAL   CHPCO, CHPSL
           INTRINSIC  CONJG
     C
     C     Initialize the array A to store the matrix A shown below.
     C     Initialize the array B to store the vector b shown below.
     C
     C          1    1+2i  1+2i         95-180i
     C     A = 1+2i   6   -2+6i    b = 545-118i
     C         1+2i -2+6i   11         865+ 62i
     C
           DATA A / (1.0,0.0), (1.0,-2.0), (6.0,0.0),
          $         (1.0,-2.0), (6.0,-2.0), (11.0,0.0) /
           DATA B / (95.0,-180.0), (545.0,-118.0), (865.0,62.0) /
     C
           PRINT 1000
           PRINT 1010, A(1), A(2), A(4)
           PRINT 1010, CONJG(A(2)), A(3), A(5)
           PRINT 1010, CONJG(A(4)), CONJG(A(5)), A(6)
           PRINT 1020
           PRINT 1030, B
           CALL CHPCO (A, N, IPIVOT, RCOND, WORK)
           PRINT 1040, RCOND
           IF ((RCOND + 1.0) .EQ. 1.0) THEN
             PRINT 1050
           END IF
           CALL CHPSL (A, N, IPIVOT, B)
           PRINT 1060
           PRINT 1030, B
     C
      1000 FORMAT (1X, 'A in full form:')
      1010 FORMAT (3(3X, '(', F4.1, ',', F4.1, ')'))
      1020 FORMAT (/1X, 'b:')
      1030 FORMAT (3X, '(', F6.1, ',', F6.1, ')')
      1040 FORMAT (/1X, 'Reciprocal condition number of A:', F6.3)
      1050 FORMAT (1X, 'A may be singular to working precision.')
      1060 FORMAT (/1X, 'A**(-1) * b:')
     C
           END

SAMPLE OUTPUT
      A in full form:
        ( 1.0, 0.0)   ( 1.0,-2.0)   ( 1.0,-2.0)
        ( 1.0, 2.0)   ( 6.0, 0.0)   ( 6.0,-2.0)
        ( 1.0, 2.0)   ( 6.0, 2.0)   (11.0, 0.0)

      b:
        (  95.0,-180.0)
        ( 545.0,-118.0)
        ( 865.0,  62.0)

      Reciprocal condition number of A: 0.001

      A**(-1) * b:
        (   5.0,   0.0)
        (  26.0,   0.0)
        (  64.0,   0.0)

Партнёры:

Хостинг: