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/* dswap.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"
/* Subroutine */ int dswap_(integer *n, doublereal *dx, integer *incx,
doublereal *dy, integer *incy)
{
/* System generated locals */
integer i__1;
/* Local variables */
integer i__, m, ix, iy, mp1;
doublereal dtemp;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* interchanges two vectors. */
/* uses unrolled loops for increments equal one. */
/* jack dongarra, linpack, 3/11/78. */
/* modified 12/3/93, array(1) declarations changed to array(*) */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* Parameter adjustments */
--dy;
--dx;
/* Function Body */
if (*n <= 0) {
return 0;
}
if (*incx == 1 && *incy == 1) {
goto L20;
}
/* code for unequal increments or equal increments not equal */
/* to 1 */
ix = 1;
iy = 1;
if (*incx < 0) {
ix = (-(*n) + 1) * *incx + 1;
}
if (*incy < 0) {
iy = (-(*n) + 1) * *incy + 1;
}
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
dtemp = dx[ix];
dx[ix] = dy[iy];
dy[iy] = dtemp;
ix += *incx;
iy += *incy;
/* L10: */
}
return 0;
/* code for both increments equal to 1 */
/* clean-up loop */
L20:
m = *n % 3;
if (m == 0) {
goto L40;
}
i__1 = m;
for (i__ = 1; i__ <= i__1; ++i__) {
dtemp = dx[i__];
dx[i__] = dy[i__];
dy[i__] = dtemp;
/* L30: */
}
if (*n < 3) {
return 0;
}
L40:
mp1 = m + 1;
i__1 = *n;
for (i__ = mp1; i__ <= i__1; i__ += 3) {
dtemp = dx[i__];
dx[i__] = dy[i__];
dy[i__] = dtemp;
dtemp = dx[i__ + 1];
dx[i__ + 1] = dy[i__ + 1];
dy[i__ + 1] = dtemp;
dtemp = dx[i__ + 2];
dx[i__ + 2] = dy[i__ + 2];
dy[i__ + 2] = dtemp;
/* L50: */
}
return 0;
} /* dswap_ */
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