Here is one possibility (note that logcontract is not always correct
for complex arguments).
(%i1) 4*atan(1/5)-atan(1/239);
(%o1) 4*atan(1/5)-atan(1/239)
(%i2) rectform(logcontract(ratsimp(logarc(%))));
(%o2) %pi/4
(%i3) cos(1/2*acos(1/3));
(%o3) cos(acos(1/3)/2)
(%i4) radcan(exponentialize(logarc(%)));
(%o4) (sqrt(2)*%i+2)/(sqrt(3)*sqrt(2*sqrt(2)*%i+1))
(%i5) rectform(%);
(%o5) sqrt(2)/sqrt(3)
Andrej
On Sun, Mar 1, 2009 at 7:23 PM, Lo?c <xlogo at free.fr> wrote:
> Hello,
>
> Does anyone know if it's possible with Maxima to compute expressions
> such as Machin's formula:
> pi/4=4arctan(1/5)-arctan(1/239)
>
> or formula such as:
>
> cos(1/2*arccos(1/3))=sqrt(6)/3
>
> If it's impossible, does anyone know if someone plan to implement it in
> Maxima?
>
> Best
>
> Lo?c
>
>
>
>
>
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