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NAME
     sgefa - compute the LU factorization of a general matrix  A.
     It is typical to follow a call to xGEFA with a call to xGESL
     to solve Ax = b or to xGEDI to compute the determinant of A.

SYNOPSIS
     SUBROUTINE DGEFA (DA, LDA, N, IPIVOT, INFO)

     SUBROUTINE SGEFA (SA, LDA, N, IPIVOT, INFO)

     SUBROUTINE ZGEFA (ZA, LDA, N, IPIVOT, INFO)

     SUBROUTINE CGEFA (CA, LDA, N, IPIVOT, INFO)



     #include <sunperf.h>

     void dgefa(double *da, int lda,  int  n,  int  *ipivot,  int
               *info) ;

     void sgefa(float *sa, int  lda,  int  n,  int  *ipivot,  int
               *info) ;

     void zgefa(doublecomplex *za, int lda, int n,  int  *ipivot,
               int *info) ;

     void cgefa(complex *ca, int lda, int  n,  int  *ipivot,  int
               *info) ;

ARGUMENTS
     xA        On entry, the matrix A.  On exit, an LU factoriza-
               tion of A.

     LDA       Leading dimension of the array A as specified in a
               dimension or type statement.  LDA >= max(1,N).

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

     IPIVOT    On exit, a vector of pivot indices.

     INFO      On exit:
               INFO = 0  Subroutine completed normally.
               INFO * 0  Returns a value k if U(k,k) = 0 to indi-
               cate that xGESL will divide by zero if called.

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER           LDA, N
           PARAMETER        (N = 3)
           PARAMETER        (LDA = N)
     C
           DOUBLE PRECISION  A(LDA,N)
           INTEGER           ICOL, INFO, IPIVOT(N), IROW
     C
           EXTERNAL          DGEFA
     C
     C     Initialize the array A to store the matrix A shown below.
     C
     C         100    2    3
     C     A = 100  202    6
     C         100  202  306
     C
           DATA A / 1.0D2, 1.0D2, 1.0D2, 2.0D0, 2.02D2, 2.02D2,
          $         3.0D0, 6.0D0, 3.06D2 /
           PRINT 1000
           PRINT 1010, ((A(IROW,ICOL), ICOL = 1, N), IROW = 1, N)
           CALL DGEFA (A, LDA, N, IPIVOT, INFO)
           IF (INFO .EQ. 0) THEN
             PRINT 1020
             PRINT 1030, (A(1,ICOL), ICOL = 1, N)
             PRINT 1040, (A(2,ICOL), ICOL = 1, N)
             PRINT 1050, (A(3,ICOL), ICOL = 1, N)
           ELSE
             PRINT 1060, INFO
           END IF
     C
      1000 FORMAT (1X, 'A:')
      1010 FORMAT (3(3X, F5.1))
      1020 FORMAT (/8X, 'Multipliers', 19X, 'Upper')
      1030 FORMAT (3X, '  1.0', 17X, 3(2X, F5.1))
      1040 FORMAT (3X, F5.1, 2X, '  1.0', 17X, 2(2X, F5.1))
      1050 FORMAT (1X, 2(2X, F5.1), 2X, '  1.0', 17X, 2X, F5.1)
      1060 FORMAT (1X, 'A appears singular at ', I2)
     C
           END

SAMPLE OUTPUT
      A:
        100.0     2.0     3.0
        100.0   202.0     6.0
        100.0   202.0   306.0

             Multipliers                   Upper
          1.0                   100.0    2.0    3.0
          1.0    1.0                   200.0    3.0
          1.0    1.0    1.0                   300.0

Партнёры:

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