| 1 | ### arctanh =====================================================================
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| 2 |
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| 3 | Tags
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| 4 | ----
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| 5 | scripting, JS, internal, treenode, general concept
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| 6 |
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| 7 | Parameters
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| 8 | ----------
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| 9 | x
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| 10 |
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| 11 | General description
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| 12 | -------------------
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| 13 | Returns the inverse hyperbolic tangent of x.
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| 14 |
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| 15 | ###
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| 16 |
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| 17 | Eval_arctanh = ->
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| 18 | push(cadr(p1))
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| 19 | Eval()
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| 20 | arctanh()
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| 21 |
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| 22 | arctanh = ->
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| 23 | d = 0.0
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| 24 | save()
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| 25 | p1 = pop()
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| 26 | if (car(p1) == symbol(TANH))
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| 27 | push(cadr(p1))
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| 28 | restore()
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| 29 | return
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| 30 |
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| 31 | if (isdouble(p1))
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| 32 | d = p1.d
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| 33 | if (d < -1.0 || d > 1.0)
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| 34 | stop("arctanh function argument is not in the interval [-1,1]")
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| 35 | d = Math.log((1.0 + d) / (1.0 - d)) / 2.0
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| 36 | push_double(d)
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| 37 | restore()
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| 38 | return
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| 39 |
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| 40 | if (iszero(p1))
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| 41 | push(zero)
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| 42 | restore()
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| 43 | return
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| 44 |
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| 45 | push_symbol(ARCTANH)
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| 46 | push(p1)
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| 47 | list(2)
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| 48 | restore()
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| 49 |
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| 50 |
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| 51 |
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