SLATEC Routines --- DTRDI ---

*DECK DTRDI
      SUBROUTINE DTRDI (T, LDT, N, DET, JOB, INFO)
C***BEGIN PROLOGUE  DTRDI
C***PURPOSE  Compute the determinant and inverse of a triangular matrix.
C***LIBRARY   SLATEC (LINPACK)
C***CATEGORY  D2A3, D3A3
C***TYPE      DOUBLE PRECISION (STRDI-S, DTRDI-D, CTRDI-C)
C***KEYWORDS  DETERMINANT, INVERSE, LINEAR ALGEBRA, LINPACK,
C             TRIANGULAR MATRIX
C***AUTHOR  Moler, C. B., (U. of New Mexico)
C***DESCRIPTION
C
C     DTRDI computes the determinant and inverse of a double precision
C     triangular matrix.
C
C     On Entry
C
C        T       DOUBLE PRECISION(LDT,N)
C                T contains the triangular matrix.  The zero
C                elements of the matrix are not referenced, and
C                the corresponding elements of the array can be
C                used to store other information.
C
C        LDT     INTEGER
C                LDT is the leading dimension of the array T.
C
C        N       INTEGER
C                N is the order of the system.
C
C        JOB     INTEGER
C                = 010       no det, inverse of lower triangular.
C                = 011       no det, inverse of upper triangular.
C                = 100       det, no inverse.
C                = 110       det, inverse of lower triangular.
C                = 111       det, inverse of upper triangular.
C
C     On Return
C
C        T       inverse of original matrix if requested.
C                Otherwise unchanged.
C
C        DET     DOUBLE PRECISION(2)
C                determinant of original matrix if requested.
C                Otherwise not referenced.
C                DETERMINANT = DET(1) * 10.0**DET(2)
C                with  1.0 .LE. ABS(DET(1)) .LT. 10.0
C                or  DET(1) .EQ. 0.0 .
C
C        INFO    INTEGER
C                INFO contains zero if the system is nonsingular
C                and the inverse is requested.
C                Otherwise INFO contains the index of
C                a zero diagonal element of T.
C
C
C***REFERENCES  J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W.
C                 Stewart, LINPACK Users' Guide, SIAM, 1979.
C***ROUTINES CALLED  DAXPY, DSCAL
C***REVISION HISTORY  (YYMMDD)
C   780814  DATE WRITTEN
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890831  Modified array declarations.  (WRB)
C   890831  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900326  Removed duplicate information from DESCRIPTION section.
C           (WRB)
C   920501  Reformatted the REFERENCES section.  (WRB)
C***END PROLOGUE  DTRDI