chico
chico - (obsolete) compute the UDU factorization and condition number of a Hermitian
matrix A. If the condition number is not needed then xHIFA is slightly
faster. It is typical to follow a call to
xHICO with a call to xHISL to solve Ax = b or to xHIDI to compute the
determinant, inverse, and inertia of A.
SUBROUTINE CHICO( A, LDA, N, IPIVOT, RCOND, WORK)
COMPLEX A(LDA,*), WORK(*)
INTEGER LDA, N
INTEGER IPIVOT(*)
REAL RCOND
SUBROUTINE CHICO_64( A, LDA, N, IPIVOT, RCOND, WORK)
COMPLEX A(LDA,*), WORK(*)
INTEGER*8 LDA, N
INTEGER*8 IPIVOT(*)
REAL RCOND
#include <sunperf.h>
void chico(complex *a, int lda, int n, int *ipivot, float *rcond);
void chico_64(complex *a, long lda, long n, long *ipivot, float *rcond);
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* A (input/output)
-
On entry, the upper triangle of the matrix A.
On exit, a UDU factorization of the matrix A. The strict lower
triangle of A is not referenced.
-
* LDA (input)
-
Leading dimension of the array A as specified in a dimension or type statement. LDA >= max(1,N).
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* N (input)
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Order of the matrix A. N >= 0.
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* IPIVOT (output)
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On exit, a vector of pivot indices.
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* RCOND (output)
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On exit, an estimate of the reciprocal condition number of
A. 0.0 >= RCOND >= 1.0. As the value of RCOND gets smaller, operations
with A such as solving Ax = b may become less stable. If RCOND
satisfies RCOND + 1.0 = 1.0 then A may be singular to working precision.
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* WORK (workspace)
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Scratch array with a dimension of N.