#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int ctrtrs_(char *uplo, char *trans, char *diag, integer *n, integer *nrhs, complex *a, integer *lda, complex *b, integer *ldb, integer *info) { /* -- LAPACK routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University September 30, 1994 Purpose ======= CTRTRS solves a triangular system of the form A * X = B, A**T * X = B, or A**H * X = B, where A is a triangular matrix of order N, and B is an N-by-NRHS matrix. A check is made to verify that A is nonsingular. Arguments ========= UPLO (input) CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular. TRANS (input) CHARACTER*1 Specifies the form of the system of equations: = 'N': A * X = B (No transpose) = 'T': A**T * X = B (Transpose) = 'C': A**H * X = B (Conjugate transpose) DIAG (input) CHARACTER*1 = 'N': A is non-unit triangular; = 'U': A is unit triangular. 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 array, dimension (LDA,N) The triangular matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced. If DIAG = 'U', the diagonal elements of A are also not referenced and are assumed to be 1. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). B (input/output) COMPLEX array, dimension (LDB,NRHS) On entry, the right hand side matrix B. On exit, if INFO = 0, 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 > 0: if INFO = i, the i-th diagonal element of A is zero, indicating that the matrix is singular and the solutions X have not been computed. ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static complex c_b2 = {1.f,0.f}; /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2; /* Local variables */ extern logical lsame_(char *, char *); extern /* Subroutine */ int ctrsm_(char *, char *, char *, char *, integer *, integer *, complex *, complex *, integer *, complex *, integer *), xerbla_(char *, integer *); static logical nounit; #define a_subscr(a_1,a_2) (a_2)*a_dim1 + a_1 #define a_ref(a_1,a_2) a[a_subscr(a_1,a_2)] a_dim1 = *lda; a_offset = 1 + a_dim1 * 1; a -= a_offset; b_dim1 = *ldb; b_offset = 1 + b_dim1 * 1; b -= b_offset; /* Function Body */ *info = 0; nounit = lsame_(diag, "N"); if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) { *info = -1; } else if (! lsame_(trans, "N") && ! lsame_(trans, "T") && ! lsame_(trans, "C")) { *info = -2; } else if (! nounit && ! lsame_(diag, "U")) { *info = -3; } else if (*n < 0) { *info = -4; } else if (*nrhs < 0) { *info = -5; } else if (*lda < max(1,*n)) { *info = -7; } else if (*ldb < max(1,*n)) { *info = -9; } if (*info != 0) { i__1 = -(*info); xerbla_("CTRTRS", &i__1); return 0; } /* Quick return if possible */ if (*n == 0) { return 0; } /* Check for singularity. */ if (nounit) { i__1 = *n; for (*info = 1; *info <= i__1; ++(*info)) { i__2 = a_subscr(*info, *info); if (a[i__2].r == 0.f && a[i__2].i == 0.f) { return 0; } /* L10: */ } } *info = 0; /* Solve A * x = b, A**T * x = b, or A**H * x = b. */ ctrsm_("Left", uplo, trans, diag, n, nrhs, &c_b2, &a[a_offset], lda, &b[ b_offset], ldb); return 0; /* End of CTRTRS */ } /* ctrtrs_ */ #undef a_ref #undef a_subscr