Maxima by Example: Chapter 1 total rewrite //ratdiff

On Jul 15, 2009, at 10:48 AM, Edwin Woollett wrote:

.....

>>
>> (%i24) ratdiff(%,x);
>> `ratdiff' variable is embedded in kernel
>> -- an error.  To debug this try debugmode(true);
>>
>> ratdiff can not handle the equation, but the message should be not an
>> obscure error message. Again a problem we have to look at.
>>
> ------------------------------------
> Thanks for your concern. A sign of a possibly intelligent machine
> might well be intelligent error messages.
> -

The message is perfectly clear to me :)

Perhaps it would be clearer to other people if it were more  
elaborate.  For example,

"ratdiff variable x is embedded in the non-rational subexpression log(x 
+1), and therefore its specially efficient method of differentiation  
cannot be used.  You can use diff(..,x) instead. "

This could be changed without offending the author of ratdiff. (me)

RJF