Zig 0.17.0-dev (Split by item)

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sqrt32

sqrt.sqrt32

fn sqrt32(z: Complex(f32)) Complex(f32)

File

lib/std/math/complex/sqrt.zig:25

Code

fn sqrt32(z: Complex(f32)) Complex(f32) {
    const x = z.re;
    const y = z.im;

    if (x == 0 and y == 0) {
        return Complex(f32).init(0, y);
    }
    if (math.isInf(y)) {
        return Complex(f32).init(math.inf(f32), y);
    }
    if (math.isNan(x)) {
        // raise invalid if y is not nan
        const t = (y - y) / (y - y);
        return Complex(f32).init(x, t);
    }
    if (math.isInf(x)) {
        // sqrt(inf + i nan)    = inf + nan i
        // sqrt(inf + iy)       = inf + i0
        // sqrt(-inf + i nan)   = nan +- inf i
        // sqrt(-inf + iy)      = 0 + inf i
        if (math.signbit(x)) {
            return Complex(f32).init(@abs(y - y), math.copysign(x, y));
        } else {
            return Complex(f32).init(x, math.copysign(y - y, y));
        }
    }

    // y = nan special case is handled fine below

    // double-precision avoids overflow with correct rounding.
    const dx = @as(f64, x);
    const dy = @as(f64, y);

    if (dx >= 0) {
        const t = @sqrt((dx + math.hypot(dx, dy)) * 0.5);
        return Complex(f32).init(
            @as(f32, @floatCast(t)),
            @as(f32, @floatCast(dy / (2.0 * t))),
        );
    } else {
        const t = @sqrt((-dx + math.hypot(dx, dy)) * 0.5);
        return Complex(f32).init(
            @as(f32, @floatCast(@abs(y) / (2.0 * t))),
            @as(f32, @floatCast(math.copysign(t, y))),
        );
    }
}