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29 lines
599 B
Prolog
29 lines
599 B
Prolog
; docformat = 'rst'
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;+
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; Inverse hyperbolic cosine. Uses the formula:
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;
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; $$\text{acosh}(z) = \ln(z + \sqrt{z + 1} \sqrt{z - 1})$$
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;
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; :Examples:
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; The arc hyperbolic sine function looks like::
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;
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; IDL> x = 2.5 * findgen(1000) / 999. + 1.
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; IDL> plot, x, mg_acosh(x), xstyle=1
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;
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; This should look like:
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;
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; .. image:: acosh.png
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;
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; :Returns:
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; float, double, complex, or double complex depending on the input
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;
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; :Params:
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; z : in, required, type=numeric
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; input
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;-
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function mg_acosh, z
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compile_opt strictarr
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return, alog(z + sqrt(z + 1) * sqrt(z - 1))
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end |