#20098: Re/Im(tanh) wrong formula
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Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.1
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by rws:
Old description:
> In analogy to #19791:
> {{{
> sage: tanh(1+2*I).n()
> 1.16673625724092 - 0.243458201185725*I
> sage: tanh(1+2*I).real().n()
> 0.202053272732553
> sage: tanh(1+2*I).imag().n()
> -0.579697798322816
> sage: tanh(x).real()
> tanh(real_part(x))/(tan(imag_part(x))^2*tanh(real_part(x))^2 + 1)
> sage: tanh(x).imag()
> tan(imag_part(x))/(tan(imag_part(x))^2*tanh(real_part(x))^2 + 1)
> }}}
> Will be fixed in Pynac-0.6.3 and should be doctested here.
New description:
In analogy to #19791:
{{{
sage: tanh(1+2*I).n()
1.16673625724092 - 0.243458201185725*I
sage: tanh(1+2*I).real().n()
0.202053272732553
sage: tanh(1+2*I).imag().n()
-0.579697798322816
sage: tanh(x).real()
tanh(real_part(x))/(tan(imag_part(x))^2*tanh(real_part(x))^2 + 1)
sage: tanh(x).imag()
tan(imag_part(x))/(tan(imag_part(x))^2*tanh(real_part(x))^2 + 1)
}}}
See for example http://dlmf.nist.gov/4.35.E36
Will be fixed in Pynac-0.6.3 and should be doctested here.
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Ticket URL: <http://trac.sagemath.org/ticket/20098#comment:1>
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