/* -- translated by f2c (version 20100827).
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"
/* Subroutine */ int igraphdsyr2k_(char *uplo, char *trans, integer *n, integer *k,
doublereal *alpha, doublereal *a, integer *lda, doublereal *b,
integer *ldb, doublereal *beta, doublereal *c__, integer *ldc)
{
/* System generated locals */
integer a_dim1, a_offset, b_dim1, b_offset, c_dim1, c_offset, i__1, i__2,
i__3;
/* Local variables */
integer i__, j, l, info;
doublereal temp1, temp2;
extern logical igraphlsame_(char *, char *);
integer nrowa;
logical upper;
extern /* Subroutine */ int igraphxerbla_(char *, integer *, ftnlen);
/* Purpose
=======
DSYR2K performs one of the symmetric rank 2k operations
C := alpha*A*B**T + alpha*B*A**T + beta*C,
or
C := alpha*A**T*B + alpha*B**T*A + beta*C,
where alpha and beta are scalars, C is an n by n symmetric matrix
and A and B are n by k matrices in the first case and k by n
matrices in the second case.
Arguments
==========
UPLO - CHARACTER*1.
On entry, UPLO specifies whether the upper or lower
triangular part of the array C is to be referenced as
follows:
UPLO = 'U' or 'u' Only the upper triangular part of C
is to be referenced.
UPLO = 'L' or 'l' Only the lower triangular part of C
is to be referenced.
Unchanged on exit.
TRANS - CHARACTER*1.
On entry, TRANS specifies the operation to be performed as
follows:
TRANS = 'N' or 'n' C := alpha*A*B**T + alpha*B*A**T +
beta*C.
TRANS = 'T' or 't' C := alpha*A**T*B + alpha*B**T*A +
beta*C.
TRANS = 'C' or 'c' C := alpha*A**T*B + alpha*B**T*A +
beta*C.
Unchanged on exit.
N - INTEGER.
On entry, N specifies the order of the matrix C. N must be
at least zero.
Unchanged on exit.
K - INTEGER.
On entry with TRANS = 'N' or 'n', K specifies the number
of columns of the matrices A and B, and on entry with
TRANS = 'T' or 't' or 'C' or 'c', K specifies the number
of rows of the matrices A and B. K must be at least zero.
Unchanged on exit.
ALPHA - DOUBLE PRECISION.
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.
A - DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is
k when TRANS = 'N' or 'n', and is n otherwise.
Before entry with TRANS = 'N' or 'n', the leading n by k
part of the array A must contain the matrix A, otherwise
the leading k by n part of the array A must contain the
matrix A.
Unchanged on exit.
LDA - INTEGER.
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. When TRANS = 'N' or 'n'
then LDA must be at least max( 1, n ), otherwise LDA must
be at least max( 1, k ).
Unchanged on exit.
B - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is
k when TRANS = 'N' or 'n', and is n otherwise.
Before entry with TRANS = 'N' or 'n', the leading n by k
part of the array B must contain the matrix B, otherwise
the leading k by n part of the array B must contain the
matrix B.
Unchanged on exit.
LDB - INTEGER.
On entry, LDB specifies the first dimension of B as declared
in the calling (sub) program. When TRANS = 'N' or 'n'
then LDB must be at least max( 1, n ), otherwise LDB must
be at least max( 1, k ).
Unchanged on exit.
BETA - DOUBLE PRECISION.
On entry, BETA specifies the scalar beta.
Unchanged on exit.
C - DOUBLE PRECISION array of DIMENSION ( LDC, n ).
Before entry with UPLO = 'U' or 'u', the leading n by n
upper triangular part of the array C must contain the upper
triangular part of the symmetric matrix and the strictly
lower triangular part of C is not referenced. On exit, the
upper triangular part of the array C is overwritten by the
upper triangular part of the updated matrix.
Before entry with UPLO = 'L' or 'l', the leading n by n
lower triangular part of the array C must contain the lower
triangular part of the symmetric matrix and the strictly
upper triangular part of C is not referenced. On exit, the
lower triangular part of the array C is overwritten by the
lower triangular part of the updated matrix.
LDC - INTEGER.
On entry, LDC specifies the first dimension of C as declared
in the calling (sub) program. LDC must be at least
max( 1, n ).
Unchanged on exit.
Further Details
===============
Level 3 Blas routine.
-- Written on 8-February-1989.
Jack Dongarra, Argonne National Laboratory.
Iain Duff, AERE Harwell.
Jeremy Du Croz, Numerical Algorithms Group Ltd.
Sven Hammarling, Numerical Algorithms Group Ltd.
=====================================================================
Test the input parameters.
Parameter adjustments */
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
b_dim1 = *ldb;
b_offset = 1 + b_dim1;
b -= b_offset;
c_dim1 = *ldc;
c_offset = 1 + c_dim1;
c__ -= c_offset;
/* Function Body */
if (igraphlsame_(trans, "N")) {
nrowa = *n;
} else {
nrowa = *k;
}
upper = igraphlsame_(uplo, "U");
info = 0;
if (! upper && ! igraphlsame_(uplo, "L")) {
info = 1;
} else if (! igraphlsame_(trans, "N") && ! igraphlsame_(trans,
"T") && ! igraphlsame_(trans, "C")) {
info = 2;
} else if (*n < 0) {
info = 3;
} else if (*k < 0) {
info = 4;
} else if (*lda < max(1,nrowa)) {
info = 7;
} else if (*ldb < max(1,nrowa)) {
info = 9;
} else if (*ldc < max(1,*n)) {
info = 12;
}
if (info != 0) {
igraphxerbla_("DSYR2K", &info, (ftnlen)6);
return 0;
}
/* Quick return if possible. */
if (*n == 0 || (*alpha == 0. || *k == 0) && *beta == 1.) {
return 0;
}
/* And when alpha.eq.zero. */
if (*alpha == 0.) {
if (upper) {
if (*beta == 0.) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = 0.;
/* L10: */
}
/* L20: */
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1];
/* L30: */
}
/* L40: */
}
}
} else {
if (*beta == 0.) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = 0.;
/* L50: */
}
/* L60: */
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1];
/* L70: */
}
/* L80: */
}
}
}
return 0;
}
/* Start the operations. */
if (igraphlsame_(trans, "N")) {
/* Form C := alpha*A*B**T + alpha*B*A**T + C. */
if (upper) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (*beta == 0.) {
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = 0.;
/* L90: */
}
} else if (*beta != 1.) {
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1];
/* L100: */
}
}
i__2 = *k;
for (l = 1; l <= i__2; ++l) {
if (a[j + l * a_dim1] != 0. || b[j + l * b_dim1] != 0.) {
temp1 = *alpha * b[j + l * b_dim1];
temp2 = *alpha * a[j + l * a_dim1];
i__3 = j;
for (i__ = 1; i__ <= i__3; ++i__) {
c__[i__ + j * c_dim1] = c__[i__ + j * c_dim1] + a[
i__ + l * a_dim1] * temp1 + b[i__ + l *
b_dim1] * temp2;
/* L110: */
}
}
/* L120: */
}
/* L130: */
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (*beta == 0.) {
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = 0.;
/* L140: */
}
} else if (*beta != 1.) {
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1];
/* L150: */
}
}
i__2 = *k;
for (l = 1; l <= i__2; ++l) {
if (a[j + l * a_dim1] != 0. || b[j + l * b_dim1] != 0.) {
temp1 = *alpha * b[j + l * b_dim1];
temp2 = *alpha * a[j + l * a_dim1];
i__3 = *n;
for (i__ = j; i__ <= i__3; ++i__) {
c__[i__ + j * c_dim1] = c__[i__ + j * c_dim1] + a[
i__ + l * a_dim1] * temp1 + b[i__ + l *
b_dim1] * temp2;
/* L160: */
}
}
/* L170: */
}
/* L180: */
}
}
} else {
/* Form C := alpha*A**T*B + alpha*B**T*A + C. */
if (upper) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
temp1 = 0.;
temp2 = 0.;
i__3 = *k;
for (l = 1; l <= i__3; ++l) {
temp1 += a[l + i__ * a_dim1] * b[l + j * b_dim1];
temp2 += b[l + i__ * b_dim1] * a[l + j * a_dim1];
/* L190: */
}
if (*beta == 0.) {
c__[i__ + j * c_dim1] = *alpha * temp1 + *alpha *
temp2;
} else {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1]
+ *alpha * temp1 + *alpha * temp2;
}
/* L200: */
}
/* L210: */
}
} else {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
temp1 = 0.;
temp2 = 0.;
i__3 = *k;
for (l = 1; l <= i__3; ++l) {
temp1 += a[l + i__ * a_dim1] * b[l + j * b_dim1];
temp2 += b[l + i__ * b_dim1] * a[l + j * a_dim1];
/* L220: */
}
if (*beta == 0.) {
c__[i__ + j * c_dim1] = *alpha * temp1 + *alpha *
temp2;
} else {
c__[i__ + j * c_dim1] = *beta * c__[i__ + j * c_dim1]
+ *alpha * temp1 + *alpha * temp2;
}
/* L230: */
}
/* L240: */
}
}
}
return 0;
/* End of DSYR2K. */
} /* igraphdsyr2k_ */