opencv/3rdparty/lapack/idamax.c

94 lines
2.0 KiB
C

/* idamax.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 "clapack.h"
integer idamax_(integer *n, doublereal *dx, integer *incx)
{
/* System generated locals */
integer ret_val, i__1;
doublereal d__1;
/* Local variables */
integer i__, ix;
doublereal dmax__;
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* finds the index of element having max. absolute value. */
/* jack dongarra, linpack, 3/11/78. */
/* modified 3/93 to return if incx .le. 0. */
/* modified 12/3/93, array(1) declarations changed to array(*) */
/* .. Local Scalars .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* Parameter adjustments */
--dx;
/* Function Body */
ret_val = 0;
if (*n < 1 || *incx <= 0) {
return ret_val;
}
ret_val = 1;
if (*n == 1) {
return ret_val;
}
if (*incx == 1) {
goto L20;
}
/* code for increment not equal to 1 */
ix = 1;
dmax__ = abs(dx[1]);
ix += *incx;
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
if ((d__1 = dx[ix], abs(d__1)) <= dmax__) {
goto L5;
}
ret_val = i__;
dmax__ = (d__1 = dx[ix], abs(d__1));
L5:
ix += *incx;
/* L10: */
}
return ret_val;
/* code for increment equal to 1 */
L20:
dmax__ = abs(dx[1]);
i__1 = *n;
for (i__ = 2; i__ <= i__1; ++i__) {
if ((d__1 = dx[i__], abs(d__1)) <= dmax__) {
goto L30;
}
ret_val = i__;
dmax__ = (d__1 = dx[i__], abs(d__1));
L30:
;
}
return ret_val;
} /* idamax_ */