John Hassler wrote:
It does exist - but it's a multivalued function, so you need a branch cut. See (halfway down the page): http://mathworld.wolfram.com/InverseHyperbolicCosine.html
john
David Cournapeau wrote:
I agree. Perhaps that is the reason for the inf here? <snip> In [18]:numpy.arccosh(0+0j) Out[18]:(-inf+0j) </snip> As it looks to me, thats not correct neither... I am using it for transforming between elliptic coordinates and rectangular ones, there this behaviour is not that desireable. Sincerely yours Pierre
Pierre SCHNIZER wrote:
Hello,
I don't know if that only happens on my machine.... For numpy 1.0 b1 I get
<snip> In [241]:numpy.arccosh(0) Out[241]:nan
I get the same results, but this is logical... acosh is defined by 0.5(exp(z) + exp(-z)) for z complex, and this cannot be smaller than 1 for z real, and never equal to 0, so arccosh(0) does not really make sense to me,
cheers,
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