/* Subroutine */ int dpftri_(char *transr, char *uplo, integer *n, doublereal
*a, integer *info)
{
/* System generated locals */
integer i__1, i__2;
/* Local variables */
integer k, n1, n2;
logical normaltransr;
extern logical lsame_(char *, char *);
extern /* Subroutine */ int dtrmm_(char *, char *, char *, char *,
integer *, integer *, doublereal *, doublereal *, integer *,
doublereal *, integer *);
logical lower;
extern /* Subroutine */ int dsyrk_(char *, char *, integer *, integer *,
doublereal *, doublereal *, integer *, doublereal *, doublereal *,
integer *), xerbla_(char *, integer *);
logical nisodd;
extern /* Subroutine */ int dlauum_(char *, integer *, doublereal *,
integer *, integer *), dtftri_(char *, char *, char *,
integer *, doublereal *, 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 */
/* ======= */
/* DPFTRI computes the inverse of a (real) 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 A is stored; */
/* = 'L': Lower triangle of A is stored. */
/* N (input) INTEGER */
/* The order of the matrix A. N >= 0. */
/* A (input/output) DOUBLE PRECISION array, dimension ( N*(N+1)/2 ) */
/* On entry, the symmetric matrix A in RFP format. RFP format is */
/* described by TRANSR, UPLO, and N as follows: If TRANSR = 'N' */
/* then RFP A is (0:N,0:k-1) when N is even; k=N/2. RFP A is */
/* (0:N-1,0:k) when N is odd; k=N/2. IF TRANSR = 'T' then RFP is */
/* the transpose of RFP A as defined when */
/* TRANSR = 'N'. The contents of RFP A are defined by UPLO as */
/* follows: If UPLO = 'U' the RFP A contains the nt elements of */
/* upper packed A. If UPLO = 'L' the RFP A contains the elements */
/* of lower packed A. The LDA of RFP A is (N+1)/2 when TRANSR = */
/* 'T'. When TRANSR is 'N' the LDA is N+1 when N is even and N */
/* is odd. See the Note below for more details. */
/* On exit, the symmetric inverse of the original matrix, in the */
/* same storage format. */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* > 0: if INFO = i, the (i,i) element of the factor U or L is */
/* zero, and the inverse could not be computed. */
/* 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. */
*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;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DPFTRI", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Invert the triangular Cholesky factor U or L. */
dtftri_(transr, uplo, "N", n, a, info);
if (*info > 0) {
return 0;
}
/* If N is odd, set NISODD = .TRUE. */
/* If N is even, set K = N/2 and NISODD = .FALSE. */
if (*n % 2 == 0) {
k = *n / 2;
nisodd = FALSE_;
} else {
nisodd = TRUE_;
}
/* Set N1 and N2 depending on LOWER */
if (lower) {
n2 = *n / 2;
n1 = *n - n2;
} else {
n1 = *n / 2;
n2 = *n - n1;
}
/* Start execution of triangular matrix multiply: inv(U)*inv(U)^C or */
/* inv(L)^C*inv(L). There are eight cases. */
if (nisodd) {
/* N is odd */
if (normaltransr) {
/* N is odd and TRANSR = 'N' */
if (lower) {
/* SRPA for LOWER, NORMAL and N is odd ( a(0:n-1,0:N1-1) ) */
/* T1 -> a(0,0), T2 -> a(0,1), S -> a(N1,0) */
/* T1 -> a(0), T2 -> a(n), S -> a(N1) */
dlauum_("L", &n1, a, n, info);
dsyrk_("L", "T", &n1, &n2, &c_b11, &a[n1], n, &c_b11, a, n);
dtrmm_("L", "U", "N", "N", &n2, &n1, &c_b11, &a[*n], n, &a[n1]
, n);
dlauum_("U", &n2, &a[*n], n, info);
} else {
/* SRPA for UPPER, NORMAL and N is odd ( a(0:n-1,0:N2-1) */
/* T1 -> a(N1+1,0), T2 -> a(N1,0), S -> a(0,0) */
/* T1 -> a(N2), T2 -> a(N1), S -> a(0) */
dlauum_("L", &n1, &a[n2], n, info);
dsyrk_("L", "N", &n1, &n2, &c_b11, a, n, &c_b11, &a[n2], n);
dtrmm_("R", "U", "T", "N", &n1, &n2, &c_b11, &a[n1], n, a, n);
dlauum_("U", &n2, &a[n1], n, info);
}
} else {
/* N is odd and TRANSR = 'T' */
if (lower) {
/* SRPA for LOWER, TRANSPOSE, and N is odd */
/* T1 -> a(0), T2 -> a(1), S -> a(0+N1*N1) */
dlauum_("U", &n1, a, &n1, info);
dsyrk_("U", "N", &n1, &n2, &c_b11, &a[n1 * n1], &n1, &c_b11,
a, &n1);
dtrmm_("R", "L", "N", "N", &n1, &n2, &c_b11, &a[1], &n1, &a[
n1 * n1], &n1);
dlauum_("L", &n2, &a[1], &n1, info);
} else {
/* SRPA for UPPER, TRANSPOSE, and N is odd */
/* T1 -> a(0+N2*N2), T2 -> a(0+N1*N2), S -> a(0) */
dlauum_("U", &n1, &a[n2 * n2], &n2, info);
dsyrk_("U", "T", &n1, &n2, &c_b11, a, &n2, &c_b11, &a[n2 * n2]
, &n2);
dtrmm_("L", "L", "T", "N", &n2, &n1, &c_b11, &a[n1 * n2], &n2,
a, &n2);
dlauum_("L", &n2, &a[n1 * n2], &n2, info);
}
}
} else {
/* N is even */
if (normaltransr) {
/* N is even and TRANSR = 'N' */
if (lower) {
/* SRPA for LOWER, NORMAL, and N is even ( a(0:n,0:k-1) ) */
/* T1 -> a(1,0), T2 -> a(0,0), S -> a(k+1,0) */
/* T1 -> a(1), T2 -> a(0), S -> a(k+1) */
i__1 = *n + 1;
dlauum_("L", &k, &a[1], &i__1, info);
i__1 = *n + 1;
i__2 = *n + 1;
dsyrk_("L", "T", &k, &k, &c_b11, &a[k + 1], &i__1, &c_b11, &a[
1], &i__2);
i__1 = *n + 1;
i__2 = *n + 1;
dtrmm_("L", "U", "N", "N", &k, &k, &c_b11, a, &i__1, &a[k + 1]
, &i__2);
i__1 = *n + 1;
dlauum_("U", &k, a, &i__1, info);
} else {
/* SRPA for UPPER, NORMAL, and N is even ( a(0:n,0:k-1) ) */
/* T1 -> a(k+1,0) , T2 -> a(k,0), S -> a(0,0) */
/* T1 -> a(k+1), T2 -> a(k), S -> a(0) */
i__1 = *n + 1;
dlauum_("L", &k, &a[k + 1], &i__1, info);
i__1 = *n + 1;
i__2 = *n + 1;
dsyrk_("L", "N", &k, &k, &c_b11, a, &i__1, &c_b11, &a[k + 1],
&i__2);
i__1 = *n + 1;
i__2 = *n + 1;
dtrmm_("R", "U", "T", "N", &k, &k, &c_b11, &a[k], &i__1, a, &
i__2);
i__1 = *n + 1;
dlauum_("U", &k, &a[k], &i__1, info);
}
} else {
/* N is even and TRANSR = 'T' */
if (lower) {
/* SRPA for LOWER, TRANSPOSE, and N is even (see paper) */
/* T1 -> B(0,1), T2 -> B(0,0), S -> B(0,k+1), */
/* T1 -> a(0+k), T2 -> a(0+0), S -> a(0+k*(k+1)); lda=k */
dlauum_("U", &k, &a[k], &k, info);
dsyrk_("U", "N", &k, &k, &c_b11, &a[k * (k + 1)], &k, &c_b11,
&a[k], &k);
dtrmm_("R", "L", "N", "N", &k, &k, &c_b11, a, &k, &a[k * (k +
1)], &k);
dlauum_("L", &k, a, &k, info);
} else {
/* SRPA for UPPER, TRANSPOSE, and N is even (see paper) */
/* T1 -> B(0,k+1), T2 -> B(0,k), S -> B(0,0), */
/* T1 -> a(0+k*(k+1)), T2 -> a(0+k*k), S -> a(0+0)); lda=k */
dlauum_("U", &k, &a[k * (k + 1)], &k, info);
dsyrk_("U", "T", &k, &k, &c_b11, a, &k, &c_b11, &a[k * (k + 1)
], &k);
dtrmm_("L", "L", "T", "N", &k, &k, &c_b11, &a[k * k], &k, a, &
k);
dlauum_("L", &k, &a[k * k], &k, info);
}
}
}
return 0;
/* End of DPFTRI */
} /* dpftri_ */
/* Subroutine */ int dpotri_(char *uplo, integer *n, doublereal *a, integer *
lda, integer *info)
{
/* -- LAPACK routine (version 3.0) --
Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
Courant Institute, Argonne National Lab, and Rice University
March 31, 1993
Purpose
=======
DPOTRI computes the inverse of a real symmetric positive definite
matrix A using the Cholesky factorization A = U**T*U or A = L*L**T
computed by DPOTRF.
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.
A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the triangular factor U or L from the Cholesky
factorization A = U**T*U or A = L*L**T, as computed by
DPOTRF.
On exit, the upper or lower triangle of the (symmetric)
inverse of A, overwriting the input factor U or L.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= 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,i) element of the factor U or L is
zero, and the inverse could not be computed.
=====================================================================
Test the input parameters.
Parameter adjustments */
/* System generated locals */
integer a_dim1, a_offset, i__1;
/* Local variables */
extern logical lsame_(char *, char *);
extern /* Subroutine */ int xerbla_(char *, integer *), dlauum_(
char *, integer *, doublereal *, integer *, integer *),
dtrtri_(char *, char *, integer *, doublereal *, integer *,
integer *);
a_dim1 = *lda;
a_offset = 1 + a_dim1 * 1;
a -= a_offset;
/* Function Body */
*info = 0;
if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < max(1,*n)) {
*info = -4;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DPOTRI", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Invert the triangular Cholesky factor U or L. */
dtrtri_(uplo, "Non-unit", n, &a[a_offset], lda, info);
if (*info > 0) {
return 0;
}
/* Form inv(U)*inv(U)' or inv(L)'*inv(L). */
dlauum_(uplo, n, &a[a_offset], lda, info);
return 0;
/* End of DPOTRI */
} /* dpotri_ */
int dpotri_(char *uplo, int *n, double *a, int *
lda, int *info)
{
/* System generated locals */
int a_dim1, a_offset, i__1;
/* Local variables */
extern int lsame_(char *, char *);
extern int xerbla_(char *, int *), dlauum_(
char *, int *, double *, int *, int *),
dtrtri_(char *, char *, int *, double *, int *,
int *);
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* DPOTRI computes the inverse of a float symmetric positive definite */
/* matrix A using the Cholesky factorization A = U**T*U or A = L*L**T */
/* computed by DPOTRF. */
/* 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. */
/* A (input/output) DOUBLE PRECISION array, dimension (LDA,N) */
/* On entry, the triangular factor U or L from the Cholesky */
/* factorization A = U**T*U or A = L*L**T, as computed by */
/* DPOTRF. */
/* On exit, the upper or lower triangle of the (symmetric) */
/* inverse of A, overwriting the input factor U or L. */
/* LDA (input) INTEGER */
/* The leading dimension of the array A. LDA >= 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,i) element of the factor U or L is */
/* zero, and the inverse could not be computed. */
/* ===================================================================== */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Test the input parameters. */
/* Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
/* Function Body */
*info = 0;
if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*lda < MAX(1,*n)) {
*info = -4;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("DPOTRI", &i__1);
return 0;
}
/* Quick return if possible */
if (*n == 0) {
return 0;
}
/* Invert the triangular Cholesky factor U or L. */
dtrtri_(uplo, "Non-unit", n, &a[a_offset], lda, info);
if (*info > 0) {
return 0;
}
/* Form inv(U)*inv(U)' or inv(L)'*inv(L). */
dlauum_(uplo, n, &a[a_offset], lda, info);
return 0;
/* End of DPOTRI */
} /* dpotri_ */
