# [Maxima] differentiating a tailor series

Stanislav Maslovski stanislav.maslovski at gmail.com
Fri Jul 4 15:48:40 CDT 2008

```On Fri, Jul 04, 2008 at 02:20:31PM +0400, Stanislav Maslovski wrote:
> Hello,
>
> I am new to maxima but find it pretty interesting to learn.
> I have tried to do the following:
>
> ============= 8< ===============
> (%i1) display2d:false;
>
> (%o1) false
> (%i2) sqrt((f - z^2/4/f)^2 + (d-z)^2) + sqrt((f - z^2/4/f)^2 + (zp-z)^2);
>
> (%o2) sqrt((zp-z)^2+(f-z^2/(4*f))^2)+sqrt((f-z^2/(4*f))^2+(d-z)^2)
> (%i3) taylor(%, [z, zp, d], 0, 4);
>
> (%o3) 2*f+(z^2+(-2*zp-2*d)*z+zp^2+d^2)/(2*f)
>          +((2*zp+2*d)*z^3+(-5*zp^2-5*d^2)*z^2+(4*zp^3+4*d^3)*z-zp^4-d^4)
> 	           /(8*f^3)
> (%i4) diff(%, z);
>
> Maxima encountered a Lisp error:
>
>  Error in PROGN [or a callee]: Bad plist ((\$ZP ((4 . 1)) 0
>                                            ((MULTI G32679 1)) ZP32684
> 					   . 5)
>                                           (\$Z ((4 . 1)) 0
>                                            ((MULTI G32679 1)) Z32685
> 					   . 6)
>                                           (G32679 ((4 . 1)) 0
>                                            ((MULTIVAR 4 (\$Z \$ZP \$D)))
>                                            G3267932686 . 7))
>
> Automatically continuing.
> To reenable the Lisp debugger set *debugger-hook* to nil.
> ============= >8 ===============
>
> Is it a bug, or am I doing something wrong?
>
> The version of maxima I use is 5.13.0.
>
> BTW, if I 'factor' the result of the taylor expansion,
> the 'diff' works after that.

In addition: 5.15.0 compiled with clisp also fails in this example.

--
Stanislav
```