spptrf - tive definite matrix A stored in packed format
SUBROUTINE SPPTRF(UPLO, N, A, INFO) CHARACTER*1 UPLO INTEGER N, INFO REAL A(*) SUBROUTINE SPPTRF_64(UPLO, N, A, INFO) CHARACTER*1 UPLO INTEGER*8 N, INFO REAL A(*) F95 INTERFACE SUBROUTINE PPTRF(UPLO, N, A, INFO) CHARACTER(LEN=1) :: UPLO INTEGER :: N, INFO REAL, DIMENSION(:) :: A SUBROUTINE PPTRF_64(UPLO, N, A, INFO) CHARACTER(LEN=1) :: UPLO INTEGER(8) :: N, INFO REAL, DIMENSION(:) :: A C INTERFACE #include <sunperf.h> void spptrf(char uplo, int n, float *a, int *info); void spptrf_64(char uplo, long n, float *a, long *info);
Oracle Solaris Studio Performance Library spptrf(3P) NAME spptrf - compute the Cholesky factorization of a real symmetric posi- tive definite matrix A stored in packed format SYNOPSIS SUBROUTINE SPPTRF(UPLO, N, A, INFO) CHARACTER*1 UPLO INTEGER N, INFO REAL A(*) SUBROUTINE SPPTRF_64(UPLO, N, A, INFO) CHARACTER*1 UPLO INTEGER*8 N, INFO REAL A(*) F95 INTERFACE SUBROUTINE PPTRF(UPLO, N, A, INFO) CHARACTER(LEN=1) :: UPLO INTEGER :: N, INFO REAL, DIMENSION(:) :: A SUBROUTINE PPTRF_64(UPLO, N, A, INFO) CHARACTER(LEN=1) :: UPLO INTEGER(8) :: N, INFO REAL, DIMENSION(:) :: A C INTERFACE #include <sunperf.h> void spptrf(char uplo, int n, float *a, int *info); void spptrf_64(char uplo, long n, float *a, long *info); PURPOSE spptrf computes the Cholesky factorization of a real symmetric positive definite matrix A stored in packed format. The factorization has the form A = U**T * U, if UPLO = 'U', or A = L * L**T, if UPLO = 'L', where U is an upper triangular matrix and L is lower triangular. ARGUMENTS UPLO (input) = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. N (input) The order of the matrix A. N >= 0. A (input/output) REAL array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the symmetric matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array A as follows: if UPLO = 'U', A(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. See below for further details. On exit, if INFO = 0, the triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, in the same storage format as A. INFO (output) = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the leading minor of order i is not posi- tive definite, and the factorization could not be completed. FURTHER DETAILS The packed storage scheme is illustrated by the following example when N = 4, UPLO = 'U': Two-dimensional storage of the symmetric matrix A: a11 a12 a13 a14 a22 a23 a24 a33 a34 (aij = aji) a44 Packed storage of the upper triangle of A: A = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ] 7 Nov 2015 spptrf(3P)