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A function that can be used in Formulas.
arcsin (x)
x.arcsin (x) is defined for -1 ≤ x ≤ 1.
   assert arcsin (-1.1) = undefined
   assert abs (arcsin (-1.0) - -pi/2) < 1e-17
   assert arcsin (0.0) = 0
   assert abs (arcsin (1.0) - pi/2) < 1e-17
   assert arcsin (1.1) = undefined
   assert arcsin (undefined) = undefined
© Paul Boersma 2023