Contents
zposv - compute the solution to a complex system of linear
equations A * X = B,
SUBROUTINE ZPOSV(UPLO, N, NRHS, A, LDA, B, LDB, INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(LDA,*), B(LDB,*)
INTEGER N, NRHS, LDA, LDB, INFO
SUBROUTINE ZPOSV_64(UPLO, N, NRHS, A, LDA, B, LDB, INFO)
CHARACTER * 1 UPLO
DOUBLE COMPLEX A(LDA,*), B(LDB,*)
INTEGER*8 N, NRHS, LDA, LDB, INFO
F95 INTERFACE
SUBROUTINE POSV(UPLO, [N], [NRHS], A, [LDA], B, [LDB], [INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:,:) :: A, B
INTEGER :: N, NRHS, LDA, LDB, INFO
SUBROUTINE POSV_64(UPLO, [N], [NRHS], A, [LDA], B, [LDB], [INFO])
CHARACTER(LEN=1) :: UPLO
COMPLEX(8), DIMENSION(:,:) :: A, B
INTEGER(8) :: N, NRHS, LDA, LDB, INFO
C INTERFACE
#include <sunperf.h>
void zposv(char uplo, int n, int nrhs, doublecomplex *a, int
lda, doublecomplex *b, int ldb, int *info);
void zposv_64(char uplo, long n, long nrhs, doublecomplex
*a, long lda, doublecomplex *b, long ldb, long
*info);
zposv computes the solution to a complex system of linear
equations
A * X = B, where A is an N-by-N Hermitian positive defin-
ite matrix and X and B are N-by-NRHS matrices.
The Cholesky decomposition is used to factor A as
A = U**H* U, if UPLO = 'U', or
A = L * L**H, if UPLO = 'L',
where U is an upper triangular matrix and L is a lower tri-
angular matrix. The factored form of A is then used to
solve the system of equations A * X = B.
UPLO (input)
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N (input) The number of linear equations, i.e., the order of
the matrix A. N >= 0.
NRHS (input)
The number of right hand sides, i.e., the number
of columns of the matrix B. NRHS >= 0.
A (input/output)
On entry, the Hermitian matrix A. If UPLO = 'U',
the leading N-by-N upper triangular part of A con-
tains the upper triangular part of the matrix A,
and the strictly lower triangular part of A is not
referenced. If UPLO = 'L', the leading N-by-N
lower triangular part of A contains the lower tri-
angular part of the matrix A, and the strictly
upper triangular part of A is not referenced.
On exit, if INFO = 0, the factor U or L from the
Cholesky factorization A = U**H*U or A = L*L**H.
LDA (input)
The leading dimension of the array A. LDA >=
max(1,N).
B (input/output)
On entry, the N-by-NRHS right hand side matrix B.
On exit, if INFO = 0, the N-by-NRHS solution
matrix X.
LDB (input)
The leading dimension of the array B. LDB >=
max(1,N).
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value
> 0: if INFO = i, the leading minor of order i of
A is not positive definite, so the factorization
could not be completed, and the solution has not
been computed.