·  Home
+   man pages
 -> Linux -> FreeBSD -> OpenBSD -> NetBSD -> Tru64 Unix -> HP-UX 11i -> IRIX
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

man pages->IRIX man pages -> complib/CHICO (3)
 Title
 Content
 Arch
 Section All Sections 1 - General Commands 2 - System Calls 3 - Subroutines 4 - Special Files 5 - File Formats 6 - Games 7 - Macros and Conventions 8 - Maintenance Commands 9 - Kernel Interface n - New Commands

### Contents

```
CHICO(3F)							     CHICO(3F)

```

### NAME[Toc][Back]

```     CHICO   - CHICO factors a complex Hermitian matrix	by elimination with
symmetric pivoting	and estimates the condition of the matrix.

If	 RCOND	is not needed, CHIFA is	slightly faster.  To solve  A*X	= B ,
follow CHICO by CHISL.  To	compute	 INVERSE(A)*C ,	follow CHICO by	CHISL.
To	compute	 INVERSE(A) , follow CHICO by CHIDI.  To compute
DETERMINANT(A) , follow CHICO by CHIDI.  To compute  INERTIA(A), follow
CHICO by CHIDI.

```

### SYNOPSYS[Toc][Back]

```      SUBROUTINE CHICO(A,LDA,N,KPVT,RCOND,Z)
```

### DESCRIPTION[Toc][Back]

```     On	Entry

A COMPLEX(LDA, N)
the Hermitian matrix to	be factored.
Only the diagonal and upper triangle are used.

LDA INTEGER
the leading dimension of the array  A .

N INTEGER
the order of the matrix	 A .  Output

A a block diagonal	matrix and the multipliers which
were used to obtain it.
The factorization can be written  A = U*D*CTRANS(U)
where  U  is a product of permutation and unit
upper triangular matrices , CTRANS(U) is the
conjugate transpose of	U , and	 D  is block diagonal
with 1 by 1 and	2 by 2 blocks.	KVPT	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

Page 1

CHICO(3F)							     CHICO(3F)

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 LINPACK CHIFA BLAS CAXPY,CDOTC,CSSCAL,SCASUM
Fortran ABS,AIMAG,AMAX1,CMPLX,CONJG,IABS,REAL

PPPPaaaaggggeeee 2222```
[ Back ]
Similar pages