Re: [Maxima-discuss] Define derivative of discontinue function

[Barton W. <wi...@un...>]

Roberts (ingenious) tellsimpafter solution (http://stackoverflow.com/questions/24892016/maxima-differentiating-a-piecewise-function/25233479#25233479) gives:

    (%i4) diff(if x^2 < 1 then x^3 else x,x);
    (%o4) if x^2<1 then 3*x^2 else 1

Not OK:

    (%i5) diff(if aa^2 < 1 then aa^3 else aa,aa);
    (%o5) if (aa^2<1)^2<1 then 3*(aa^2<1)^2 else 1

Might a workaround be

block([aa : gensym(), bb : gensym(), cc : gensym(),xx : gensym()],
    matchdeclare ([aa, bb, cc], all, xx, symbolp),
    tellsimpafter ('diff(if aa then bb else cc,xx), buildq([aa,dbb : diff(bb,xx),dcc : diff(cc,xx)], if aa then dbb else dcc)));

--Barton