; docformat = 'rst' ;+ ; Inverse hyperbolic sine. Uses the formula: ; ; $$\text{asinh}(z) = \ln(z + \sqrt{1 + z^2})$$ ; ; :Examples: ; The arc hyperbolic sine function looks like:: ; ; IDL> x = 10. * findgen(1000) / 999. - 5. ; IDL> plot, x, mg_asinh(x), xstyle=1 ; ; This should look like: ; ; .. image:: asinh.png ; ; :Returns: ; float, double, complex, or double complex depending on the input ; ; :Params: ; z : in, required, type=numeric ; input ;- function mg_asinh, z compile_opt strictarr return, alog(z + sqrt(1 + z*z)) end