Aliasing is prevented in digital systems by an anti-aliasing filter. Aliasing analysers intend to make and compute useful information for understanding aliasing in programs. Another optimization impacted by aliasing is code reordering. This condition is called error masking or aliasing. This is usually visible as aliasing or shadow continuity glitches. During sampling the aliasing modifies the cutoff parameters. They are intended to increase rendering speed and reduce aliasing artifacts. The illusion is caused by temporal aliasing, commonly known as the stroboscopic effect. Temporal anti-aliasing (TAA) seeks to reduce or remove the effects of temporal aliasing. Conversely, computing precise aliasing requires a call graph. Some amount of aliasing always occurs when such functions are sampled. This axiom may be strengthened to exclude also partial aliasing with other instances. Alias analysers intend to make and compute useful information for understanding aliasing in programs. Note that both these problems address the aliasing issue. The XOR swap is also complicated in practice by aliasing.