Function taylor - bug or feature?

I looks like a bug to me to; possible workaround:

(%i8) load("pdiff")$

(%i9) G : diff(a(x,z),x,1);
(%o9) a[(1,0)](x,z)

(%i10) taylor(G,z,0,1);
(%o10) a[(1,0)](x,0)+a[(1,1)](x,0)*z+...

Barton

-----maxima-bounces at math.utexas.edu wrote: -----

>When?I?apply?the?function?'taylor(function,z,...,?...)'?to?a?function
>containing?the?d/dz?operator,?it?works?correctly.??However?if?the
>differential?is?of?another?variable?it?fails.??Thus:
>=================================
>(%i1)?G?:?diff(a(x,z),z,1);
>?????????????????????????????????d
>(%o1)???????????????????????????--?(a(x,?z))
>?????????????????????????????????dz
>(%i2)?H?:?taylor(G,z,0,1);
>????????????????????????????????????????????????!
>?????????????????????????!??????????2???????????!
>?????????????d???????????!?????????d????????????!
>(%o2)/T/????--?(a(x,?z))!??????+?(---?(a(x,?z))!?????)?z?+?.?.?.
>?????????????dz??????????!???????????2??????????!
>?????????????????????????!z?=?0????dz???????????!
>????????????????????????????????????????????????!z?=?0
>=================================
>
>works,?but:
>
>=================================
>(%i3)?G?:?diff(a(x,z),x,1);
>?????????????????????????????????d
>(%o3)???????????????????????????--?(a(x,?z))
>?????????????????????????????????dx
>(%i4)?H?:?taylor(G,z,0,1);
>?????????????????????????????d
>(%o4)/T/????????????????????--?(a(x,?z))?+?.?.?.
>?????????????????????????????dx
>=================================
>
>fails.
>
>I?presume?this?is?a?bug.
>
>Regards,
>
>David?Webb.
>
>
>
>
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