Numerology and numerological divination by systems such as isopsephy were popular among early mathematicians, such as Pythagoras, but are no longer considered part of mathematics and are regarded as pseudomathematics by modern scientists. This is similar to the historical relationships between astrology and astronomy, and between alchemy and chemistry. Today, numerology is often associated with the occult, alongside astrology and similar divinatory arts. The term “numerology” can also be used for those who place excess faith in numerical patterns, even if those people don't practice traditional numerology. For example, in his 1997 book Numerology: Or What Pythagoras Wrought, mathematician Underwood Dudley uses the term to discuss practitioners of the Elliott wave principle of stock market analysis.