zgeco
zgeco - (obsolete) compute the LU factorization and estimate the condition number of a
general matrix A. If the condition number is not needed then CGEFA is slightly faster. It is typical to follow a call
to CGECO with a call to CGESL to solve Ax = b or to CGEDI to compute the determinant and inverse of A.
SUBROUTINE ZGECO( A, LDA, N, IPIVOT, RCOND, WORK)
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER LDA, N
INTEGER IPIVOT(*)
DOUBLE PRECISION RCOND
SUBROUTINE ZGECO_64( A, LDA, N, IPIVOT, RCOND, WORK)
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER*8 LDA, N
INTEGER*8 IPIVOT(*)
DOUBLE PRECISION RCOND
#include <sunperf.h>
void zgeco(doublecomplex *a, int lda, int n, int *ipivot, double *rcond);
void zgeco_64(doublecomplex *a, long lda, long n, long *ipivot, double *rcond);
-
* A (input/output)
-
On entry, the matrix A.
On exit, an LU factorization of A.
-
* LDA (input)
-
Leading dimension of the array A as specified in a dimension or
type statement. LDA >= max(1,N).
-
* N (input)
-
Order of the matrix A. N >= 0.
-
* IPIVOT (output)
-
On exit, a vector of pivot indices.
-
* RCOND (output)
-
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.
-
* WORK (workspace)
-
Scratch array with a dimension of N.