/* dpftrs.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static doublereal c_b10 = 1.;
/* Subroutine */ int dpftrs_(char *transr, char *uplo, integer *n, integer *
nrhs, doublereal *a, doublereal *b, integer *ldb, integer *info)
{
/* System generated locals */
integer b_dim1, b_offset, i__1;
/* Local variables */
logical normaltransr;
extern logical lsame_(char *, char *);
extern /* Subroutine */ int dtfsm_(char *, char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, doublereal *,
integer *);
logical lower;
extern /* Subroutine */ int xerbla_(char *, integer *);
/* -- LAPACK routine (version 3.2) -- */
/* -- Contributed by Fred Gustavson of the IBM Watson Research Center -- */
/* -- November 2008 -- */
/* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
/* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DPFTRS solves a system of linear equations A*X = B with a symmetric */
/* positive definite matrix A using the Cholesky factorization */
/* A = U**T*U or A = L*L**T computed by DPFTRF. */
/* Arguments */
/* ========= */
/* TRANSR (input) CHARACTER */
/* = 'N': The Normal TRANSR of RFP A is stored; */
/* = 'T': The Transpose TRANSR of RFP A is stored. */
/* UPLO (input) CHARACTER */
/* = 'U': Upper triangle of RFP A is stored; */
/* = 'L': Lower triangle of RFP 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) DOUBLE PRECISION array, dimension ( N*(N+1)/2 ). */
/* The triangular factor U or L from the Cholesky factorization */
/* of RFP A = U**T*U or RFP A = L*L**T, as computed by DPFTRF. */
/* See note below for more details about RFP A. */
/* B (input/output) DOUBLE PRECISION 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 */
/* Notes */
/* ===== */
/* We first consider Rectangular Full Packed (RFP) Format when N is */
/* even. We give an example where N = 6. */
/* AP is Upper AP is Lower */
/* 00 01 02 03 04 05 00 */
/* 11 12 13 14 15 10 11 */
/* 22 23 24 25 20 21 22 */
/* 33 34 35 30 31 32 33 */
/* 44 45 40 41 42 43 44 */
/* 55 50 51 52 53 54 55 */
/* Let TRANSR = 'N'. RFP holds AP as follows: */
/* For UPLO = 'U' the upper trapezoid A(0:5,0:2) consists of the last */
/* three columns of AP upper. The lower triangle A(4:6,0:2) consists of */
/* the transpose of the first three columns of AP upper. */
/* For UPLO = 'L' the lower trapezoid A(1:6,0:2) consists of the first */
/* three columns of AP lower. The upper triangle A(0:2,0:2) consists of */
/* the transpose of the last three columns of AP lower. */
/* This covers the case N even and TRANSR = 'N'. */
/* RFP A RFP A */
/* 03 04 05 33 43 53 */
/* 13 14 15 00 44 54 */
/* 23 24 25 10 11 55 */
/* 33 34 35 20 21 22 */
/* 00 44 45 30 31 32 */
/* 01 11 55 40 41 42 */
/* 02 12 22 50 51 52 */
/* Now let TRANSR = 'T'. RFP A in both UPLO cases is just the */
/* transpose of RFP A above. One therefore gets: */
/* RFP A RFP A */
/* 03 13 23 33 00 01 02 33 00 10 20 30 40 50 */
/* 04 14 24 34 44 11 12 43 44 11 21 31 41 51 */
/* 05 15 25 35 45 55 22 53 54 55 22 32 42 52 */
/* We first consider Rectangular Full Packed (RFP) Format when N is */
/* odd. We give an example where N = 5. */
/* AP is Upper AP is Lower */
/* 00 01 02 03 04 00 */
/* 11 12 13 14 10 11 */
/* 22 23 24 20 21 22 */
/* 33 34 30 31 32 33 */
/* 44 40 41 42 43 44 */
/* Let TRANSR = 'N'. RFP holds AP as follows: */
/* For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last */
/* three columns of AP upper. The lower triangle A(3:4,0:1) consists of */
/* the transpose of the first two columns of AP upper. */
/* For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first */
/* three columns of AP lower. The upper triangle A(0:1,1:2) consists of */
/* the transpose of the last two columns of AP lower. */
/* This covers the case N odd and TRANSR = 'N'. */
/* RFP A RFP A */
/* 02 03 04 00 33 43 */
/* 12 13 14 10 11 44 */
/* 22 23 24 20 21 22 */
/* 00 33 34 30 31 32 */
/* 01 11 44 40 41 42 */
/* Now let TRANSR = 'T'. RFP A in both UPLO cases is just the */
/* transpose of RFP A above. One therefore gets: */
/* RFP A RFP A */
/* 02 12 22 00 01 00 10 20 30 40 50 */
/* 03 13 23 33 11 33 11 21 31 41 51 */
/* 04 14 24 34 44 43 44 22 32 42 52 */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
/* Function Body */
*info = 0;
normaltransr = lsame_(transr, "N");
lower = lsame_(uplo, "L");
if (! normaltransr && ! lsame_(transr, "T")) {
*info = -1;
} else if (! lower && ! lsame_(uplo, "U")) {
*info = -2;
} else if (*n < 0) {
*info = -3;
} else if (*nrhs < 0) {
*info = -4;
} else if (*ldb < max(1,*n)) {
*info = -7;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DPFTRS", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0 || *nrhs == 0) {
return 0;
}
/* start execution: there are two triangular solves */
if (lower) {
dtfsm_(transr, "L", uplo, "N", "N", n, nrhs, &c_b10, a, &b[b_offset],
ldb);
dtfsm_(transr, "L", uplo, "T", "N", n, nrhs, &c_b10, a, &b[b_offset],
ldb);
} else {
dtfsm_(transr, "L", uplo, "T", "N", n, nrhs, &c_b10, a, &b[b_offset],
ldb);
dtfsm_(transr, "L", uplo, "N", "N", n, nrhs, &c_b10, a, &b[b_offset],
ldb);
}
return 0;
/* End of DPFTRS */
} /* dpftrs_ */
