common/complex/csqrtf.c

	csqrtf.c revision ddc0e0b53c661f6e439e3b7072b3ef353eadb4af
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak __csqrtf = csqrtf

#include "libm.h"       /* sqrt/fabsf/sqrtf */
#include "complex_wrapper.h"

/* INDENT OFF */
static const float zero = 0.0F;
/* INDENT ON */

fcomplex
csqrtf(fcomplex z) {
    fcomplex ans;
    double dt, dx, dy;
    float x, y, t, ax, ay, w;
    int ix, iy, hx, hy;

    x = F_RE(z);
    y = F_IM(z);
    hx = THE_WORD(x);
    hy = THE_WORD(y);
    ix = hx & 0x7fffffff;
    iy = hy & 0x7fffffff;
    ay = fabsf(y);
    ax = fabsf(x);
    if (ix >= 0x7f800000 || iy >= 0x7f800000) {
        /* x or y is Inf or NaN */
        if (iy == 0x7f800000)
            F_IM(ans) = F_RE(ans) = ay;
        else if (ix == 0x7f800000) {
            if (hx > 0) {
                F_RE(ans) = ax;
                F_IM(ans) = ay * zero;
            } else {
                F_RE(ans) = ay * zero;
                F_IM(ans) = ax;
            }
        } else
            F_IM(ans) = F_RE(ans) = ax + ay;
    } else if (iy == 0) {
        if (hx >= 0) {
            F_RE(ans) = sqrtf(ax);
            F_IM(ans) = zero;
        } else {
            F_IM(ans) = sqrtf(ax);
            F_RE(ans) = zero;
        }
    } else {
        dx = (double) ax;
        dy = (double) ay;
        dt = sqrt(0.5 * (sqrt(dx * dx + dy * dy) + dx));
        t = (float) dt;
        w = (float) (dy / (dt + dt));
        if (hx >= 0) {
            F_RE(ans) = t;
            F_IM(ans) = w;
        } else {
            F_IM(ans) = t;
            F_RE(ans) = w;
        }
    }
    if (hy < 0)
        F_IM(ans) = -F_IM(ans);
    return (ans);
}