isOddInteger

fn isOddInteger(x: f64) bool {
    if (@abs(x) >= 1 << 53) {
        // From https://golang.org/src/math/pow.go
        // 1 << 53 is the largest exact integer in the float64 format.
        // Any number outside this range will be truncated before the decimal point and therefore will always be
        // an even integer.
        // Without this check and if x overflows i64 the @intFromFloat(r.ipart) conversion below will panic
        return false;
    }
    const r = math.modf(x);
    return r.fpart == 0.0 and @as(i64, @intFromFloat(r.ipart)) & 1 == 1;
}