csifa
csifa - (obsolete) compute the UDU factorization of a symmetric matrix A. It is typical to
follow a call to CSIFA with a call to CSISL to solve Ax = b or to CSIDI
to compute the determinant, inverse, and inertia of A.
SUBROUTINE CSIFA( A, LDA, N, IPIVOT, INFO)
COMPLEX A(LDA,*)
INTEGER LDA, N, INFO
INTEGER IPIVOT(*)
SUBROUTINE CSIFA_64( A, LDA, N, IPIVOT, INFO)
COMPLEX A(LDA,*)
INTEGER*8 LDA, N, INFO
INTEGER*8 IPIVOT(*)
#include <sunperf.h>
void csifa(complex *a, int lda, int n, int *ipivot, int *info);
void csifa_64(complex *a, long lda, long n, long *ipivot, long *info);
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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).
-
* N (input)
-
Order of the matrix A. N >= 0.
-
* IPIVOT (output)
-
On exit, a vector of pivot indices.
-
* INFO (output)
-
On exit:
INFO = 0 Subroutine completed normally.
INFO > 0 Returns a value k if the kth pivot block is singular to
indicate that CSISL or CSIDI will divide by zero if called.