CAS not always working with trigonometric formulas ?



thomas x wrote:

> Hello all
> I have a simple question : "cos(%pi/4)" gives me "SQRT(2)/2" but
> tan(%pi/8) gives me "TAN(%PI/8)" instead of "SQRT(2)-1", why ?
> Best regards
> Thomas
> 
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Short answer: it's not programmed to do that.

Longer answer: Do you always want to do that? Sometimes
the radical expression is much longer. e.g.

tan(%pi/16) or  SQRT(2-SQRT(2))*(SQRT(2)+2)*(2-SQRT(SQRT(2)+2))/2

There is a flag %piargs   which should control the conversion,
but apparently does not.

Commercial macsyma does better here.

RJF