#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int zpotrs_(char *uplo, integer *n, integer *nrhs, doublecomplex *a, integer *lda, doublecomplex *b, integer *ldb, integer *info) { /* -- LAPACK routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= ZPOTRS solves a system of linear equations A*X = B with a Hermitian positive definite matrix A using the Cholesky factorization A = U**H*U or A = L*L**H computed by ZPOTRF. Arguments ========= UPLO (input) CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. N (input) INTEGER The order of the matrix A. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. A (input) COMPLEX*16 array, dimension (LDA,N) The triangular factor U or L from the Cholesky factorization A = U**H*U or A = L*L**H, as computed by ZPOTRF. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). B (input/output) COMPLEX*16 array, dimension (LDB,NRHS) On entry, the right hand side matrix B. On exit, the solution matrix X. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static doublecomplex c_b1 = {1.,0.}; /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1; /* Local variables */ extern logical lsame_(char *, char *); static logical upper; extern /* Subroutine */ int ztrsm_(char *, char *, char *, char *, integer *, integer *, doublecomplex *, doublecomplex *, integer *, doublecomplex *, integer *), xerbla_(char *, integer *); a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; b_dim1 = *ldb; b_offset = 1 + b_dim1; b -= b_offset; /* Function Body */ *info = 0; upper = lsame_(uplo, "U"); if (! upper && ! lsame_(uplo, "L")) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*nrhs < 0) { *info = -3; } else if (*lda < max(1,*n)) { *info = -5; } else if (*ldb < max(1,*n)) { *info = -7; } if (*info != 0) { i__1 = -(*info); xerbla_("ZPOTRS", &i__1); return 0; } /* Quick return if possible */ if (*n == 0 || *nrhs == 0) { return 0; } if (upper) { /* Solve A*X = B where A = U'*U. Solve U'*X = B, overwriting B with X. */ ztrsm_("Left", "Upper", "Conjugate transpose", "Non-unit", n, nrhs, & c_b1, &a[a_offset], lda, &b[b_offset], ldb); /* Solve U*X = B, overwriting B with X. */ ztrsm_("Left", "Upper", "No transpose", "Non-unit", n, nrhs, &c_b1, & a[a_offset], lda, &b[b_offset], ldb); } else { /* Solve A*X = B where A = L*L'. Solve L*X = B, overwriting B with X. */ ztrsm_("Left", "Lower", "No transpose", "Non-unit", n, nrhs, &c_b1, & a[a_offset], lda, &b[b_offset], ldb); /* Solve L'*X = B, overwriting B with X. */ ztrsm_("Left", "Lower", "Conjugate transpose", "Non-unit", n, nrhs, & c_b1, &a[a_offset], lda, &b[b_offset], ldb); } return 0; /* End of ZPOTRS */ } /* zpotrs_ */