SUBROUTINE DTRDI(T,LDT,N,DET,JOB,INFO)
C***BEGIN PROLOGUE  DTRDI
C***DATE WRITTEN   780814   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  D2A3,D3A3
C***KEYWORDS  DETERMINANT,DOUBLE PRECISION,INVERSE,LINEAR ALGEBRA,
C             LINPACK,MATRIX,TRIANGULAR
C***AUTHOR  MOLER, C. B., (U. OF NEW MEXICO)
C***PURPOSE  Computes the determinant and inverse of a d.p. TRIANGULAR
C            matrix.
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. DABS(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     LINPACK.  This version dated 08/14/78 .
C     Cleve Moler, University of New Mexico, Argonne National Lab.
C
C     Subroutines and Functions
C
C     BLAS DAXPY,DSCAL
C     Fortran DABS,MOD
C***REFERENCES  DONGARRA J.J., BUNCH J.R., MOLER C.B., STEWART G.W.,
C                 *LINPACK USERS  GUIDE*, SIAM, 1979.
C***ROUTINES CALLED  DAXPY,DSCAL
C***END PROLOGUE  DTRDI