DTRCO(3F)

NAME
     DTRCO   - DTRCO estimates the condition of a double precision triangular
     matrix.


SYNOPSYS
      SUBROUTINE DTRCO(T,LDT,N,RCOND,Z,JOB)

DESCRIPTION
     On Entry

     T DOUBLE PRECISION(LDT,N)
        T contains the triangular matrix.  The zero
        elements of the matrix are not referenced, and
        the corresponding elements of the array can be
        used to store other information.

     LDT INTEGER
        LDT is the leading dimension of the array T.

     N INTEGER
        N is the order of the system.

     JOB INTEGER
        = 0         T  is lower triangular.
        = nonzero   T  is upper triangular.  On Return

     RCOND DOUBLE PRECISION
        an estimate of the reciprocal condition of  T .
        For the system  T*X = B , relative perturbations
        in  T  and  B  of size  EPSILON  may cause
        relative perturbations in  X  of size  EPSILON/RCOND .
        If  RCOND  is so small that the logical expression
        1.0 + RCOND .EQ. 1.0
        is true, then  T  may be singular to working
        precision.  In particular,  RCOND  is zero  if
        exact singularity is detected or the estimate
        underflows.

     Z DOUBLE PRECISION(N)
        a work vector whose contents are usually unimportant.
        If  T  is close to a singular matrix, then  Z  is
        an approximate null vector in the sense that
        NORM(A*Z) = RCOND*NORM(A)*NORM(Z) .  LINPACK.  This version dated
     08/14/78 .  Cleve Moler, University of New Mexico, Argonne National Lab.
     Subroutines and Functions BLAS DAXPY,DSCAL,DASUM Fortran DABS,DMAX1,DSIGN