Fear of trains the social norms of a realistic fear, this anxiety may be classified as a specific phobia about trains. "Campbell's Psychiatric Dictionary" puts fear of trains under the "vehicle phobia", together with fears of boats, airplanes, automobiles, and other forms of transportation. A 1913 short story "Terror" by Jun'ichirō Tanizaki is a first-person narrative of a young man suffering of the morbid fear of travel in trains and streetcars. Tanizaki uses the German word , "railroad sickness". Other travel-related anxieties include: Other transport-related disorders include: Fear of trains The fear of trains is anxiety and fear associated with trains, railways, and
Irrational number number to ratios of continuous magnitude. In his commentary on Book 10 of the "Elements", the Persian mathematician Al-Mahani (d. 874/884) examined and classified quadratic irrationals and cubic irrationals. He provided definitions for rational and irrational magnitudes, which he treated as irrational numbers. He dealt with them freely but explains them in geometric terms as follows: In contrast to Euclid's concept of magnitudes as lines, Al-Mahani considered integers and fractions as rational magnitudes, and square roots and cube roots as irrational magnitudes. He also introduced an arithmetical approach to the concept of irrationality, as he attributes the following to irrational