zdotc.c

来自「InsightToolkit-1.4.0(有大量的优化算法程序)」· C语言 代码 · 共 54 行

#include "f2c.h"
#include "netlib.h"

/* Modified by Peter Vanroose, June 2001: manual optimisation and clean-up */
/*                               and moved out of zsvdc.c to separate file */

/* Double Complex */ void zdotc_(ret_val, n, zx, incx, zy, incy)
doublecomplex *ret_val;
const integer *n;
const doublecomplex *zx;
const integer *incx;
const doublecomplex *zy;
const integer *incy;
{
    /* Local variables */
    static integer i;
    static doublecomplex ztemp;
    static integer ix, iy;

/*     forms the dot product of two vectors, conjugating the first vector */
/*           */
/*     jack dongarra, 3/11/78. */
/*     modified 12/3/93, array(1) declarations changed to array(*) */

    if (*n <= 0) {
        ret_val->r = 0., ret_val->i = 0.;
        return;
    }
    ztemp.r = 0., ztemp.i = 0.;

    if (*incx == 1 && *incy == 1) {
        for (i = 0; i < *n; ++i) {
            ztemp.r += zx[i].r * zy[i].r + zx[i].i * zy[i].i,
            ztemp.i += zx[i].r * zy[i].i - zx[i].i * zy[i].r;
        }
        ret_val->r = ztemp.r, ret_val->i = ztemp.i;
    }
    else {
        ix = 0; iy = 0;
        if (*incx < 0) {
            ix = (1-(*n)) * *incx;
        }
        if (*incy < 0) {
            iy = (1-(*n)) * *incy;
        }
        for (i = 0; i < *n; ++i) {
            ztemp.r += zx[ix].r * zy[iy].r + zx[ix].i * zy[iy].i,
            ztemp.i += zx[ix].r * zy[iy].i - zx[ix].i * zy[iy].r;
            ix += *incx; iy += *incy;
        }
        ret_val->r = ztemp.r, ret_val->i = ztemp.i;
    }
} /* zdotc_ */