CGECO man page on IRIX

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CGECO(3F)							     CGECO(3F)

NAME
     CGECO   - CGECO factors a complex matrix by Gaussian elimination and
     estimates the condition of the matrix.

     If	 RCOND	is not needed, CGEFA is slightly faster.  To solve  A*X = B ,
     follow CGECO By CGESL.  To Compute	 INVERSE(A)*C , follow CGECO by CGESL.
     To compute	 DETERMINANT(A) , follow CGECO by CGEDI.  To compute
     INVERSE(A) , follow CGECO by CGEDI.

SYNOPSYS
      SUBROUTINE CGECO(A,LDA,N,IPVT,RCOND,Z)

DESCRIPTION
     On Entry

     A COMPLEX(LDA, N)
	the matrix to be factored.

     LDA INTEGER
	the leading dimension of the array  A .

     N INTEGER
	the order of the matrix	 A .  On Return

     A an upper triangular matrix and the multipliers
	which were used to obtain it.
	The factorization can be written  A = L*U  where
	L  is a product of permutation and unit lower
	triangular matrices and	 U  is upper triangular.

     IPVT INTEGER(N)
	an integer vector of pivot indices.

     RCOND REAL
	an estimate of the reciprocal condition of  A .
	For the system	A*X = B , relative perturbations
	in  A  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  A  may be singular to working
	precision.  In particular,  RCOND  is zero  if
	exact singularity is detected or the estimate
	underflows.

     Z COMPLEX(N)
	a work vector whose contents are usually unimportant.
	If  A  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.

									Page 1

CGECO(3F)							     CGECO(3F)

     Subroutines and Functions LINPACK CGEFA BLAS CAXPY,CDOTC,CSSCAL,SCASUM
     Fortran ABS,AIMAG,AMAX1,CMPLX,CONJG,REAL

									Page 2

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