Hi Ted,
(%i2) trigsimp(sin(x)-cos(x)^2*sin(x));
(%o2) sin(x)^3
(%i3) sin(x)-cos(x)^2*sin(x), trigsimp;
(%o3) sin(x)-cos(x)^2*sin(x)
(%i4) ratsimp(sin(x)-cos(x)^2*sin(x));
(%o4) (1-cos(x)^2)*sin(x)
(%i5) sin(x)-cos(x)^2*sin(x), ratsimp;
(%o5) (1-cos(x)^2)*sin(x)
ratsimp has the evfun (see ? evfun) property, trigsimp has not.
(%i6) declare(trigsimp, evfun)$
(%i7) sin(x)-cos(x)^2*sin(x), trigsimp;
(%o7) sin(x)^3
HTH
Volker van Nek
Am 21 Aug 2008 um 10:01 hat Edwin Woollett geschrieben:
> is there a deep reason ratsimp and trigsimp act differently
> in the effective interactive ev(...) examples:
>
> (%i1) display2d:false$
> (%i2) integrate(x^2*erf(x),x);
> (%o2) (%pi*x^3*erf(x)+(sqrt(%pi)*x^2+sqrt(%pi))*%e^-x^2)/(3*%pi)
> (%i3) diff(%,x),ratsimp;
> (%o3) x^2*erf(x)
> (%i4) integrate(sin(x)^3,x);
> (%o4) cos(x)^3/3-cos(x)
> (%i5) diff(%,x), trigsimp;
> (%o5) sin(x)-cos(x)^2*sin(x)
> (%i6) trigsimp(%);
> (%o6) sin(x)^3
> Based on the ratsimp use in the first example
> I would have expected the trigsimp use in
> the second to have done trigsimp(diff(...) ).
>
> Ted Woollett
>
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