const std = @import("std");
const N = 20000000;
var a: [N]f64 = undefined;
pub fn main() void {
    var i: usize = 0;
    while (i < N) : (i += 1) a[i] = @as(f64, @floatFromInt(i % 1000)) * 0.001;
    var acc: @Vector(4, f64) = @splat(0.0);
    const limit = (N / 4) * 4;
    i = 0;
    while (i < limit) : (i += 4) {
        const v: @Vector(4, f64) = a[i..][0..4].*;
        acc += v * v;
    }
    var sum: f64 = @reduce(.Add, acc);
    while (i < N) : (i += 1) sum += a[i] * a[i];
    std.debug.print("{d:.6}\n", .{sum});
}