Files
lammps/lib/linalg/dsyr.cpp

101 lines
2.8 KiB
C++

#ifdef __cplusplus
extern "C" {
#endif
#include "lmp_f2c.h"
int dsyr_(char *uplo, integer *n, doublereal *alpha, doublereal *x, integer *incx, doublereal *a,
integer *lda, ftnlen uplo_len)
{
integer a_dim1, a_offset, i__1, i__2;
integer i__, j, ix, jx, kx, info;
doublereal temp;
extern logical lsame_(char *, char *, ftnlen, ftnlen);
extern int xerbla_(char *, integer *, ftnlen);
--x;
a_dim1 = *lda;
a_offset = 1 + a_dim1;
a -= a_offset;
info = 0;
if (!lsame_(uplo, (char *)"U", (ftnlen)1, (ftnlen)1) && !lsame_(uplo, (char *)"L", (ftnlen)1, (ftnlen)1)) {
info = 1;
} else if (*n < 0) {
info = 2;
} else if (*incx == 0) {
info = 5;
} else if (*lda < max(1, *n)) {
info = 7;
}
if (info != 0) {
xerbla_((char *)"DSYR ", &info, (ftnlen)6);
return 0;
}
if (*n == 0 || *alpha == 0.) {
return 0;
}
if (*incx <= 0) {
kx = 1 - (*n - 1) * *incx;
} else if (*incx != 1) {
kx = 1;
}
if (lsame_(uplo, (char *)"U", (ftnlen)1, (ftnlen)1)) {
if (*incx == 1) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (x[j] != 0.) {
temp = *alpha * x[j];
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] += x[i__] * temp;
}
}
}
} else {
jx = kx;
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (x[jx] != 0.) {
temp = *alpha * x[jx];
ix = kx;
i__2 = j;
for (i__ = 1; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] += x[ix] * temp;
ix += *incx;
}
}
jx += *incx;
}
}
} else {
if (*incx == 1) {
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (x[j] != 0.) {
temp = *alpha * x[j];
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] += x[i__] * temp;
}
}
}
} else {
jx = kx;
i__1 = *n;
for (j = 1; j <= i__1; ++j) {
if (x[jx] != 0.) {
temp = *alpha * x[jx];
ix = jx;
i__2 = *n;
for (i__ = j; i__ <= i__2; ++i__) {
a[i__ + j * a_dim1] += x[ix] * temp;
ix += *incx;
}
}
jx += *incx;
}
}
}
return 0;
}
#ifdef __cplusplus
}
#endif