On Sun, 10 Apr 2016 11:33:59 +0200, "Richard B. Kreckel" <kreckel@in.terlu.de> said:
RK> On 04/10/2016 12:23 AM, Vladimir V. Kisil wrote: >>>>>>> On Sat, 9 Apr 2016 23:59:36 +0200, "Richard B. Kreckel" >>>>>>> <kreckel@in.terlu.de> said: >> >> f(x,y).diff(x, 3).diff(y, 2) >> which is printed as >> >> D[0,0,0,1,1](f)(x,y) >> This is fantastic. >> RK> Hmmm... Wouldn't it be more fantastic if it were printed RK> D[x,x,x,y,y](f)(x,y)? >> >> But how to print f(x+y,x-y).diff(x, 3).diff(y, 2) in this case? RK> Well, I would have supposed like this: RK> D[x+y,x+y,x+y,x+y,x+y](f)(x+y,x-y)+D[x+y,x+y,x+y,x+y,x-y](f)(x+y,x-y)-2*D[x+y,x+y,x+y,x-y,x-y](f)(x+y,x-y)-2*D[x+y,x+y,x-y,x-y,x-y](f)(x+y,x-y)+D[x+y,x-y,x-y,x-y,x-y](f)(x+y,x-y)+D[x-y,x-y,x-y,x-y,x-y](f)(x+y,x-y) Yet, from a purist point of view, I have a concern that for f(x,x).diff(x, 3) the print-out will be ambiguous... -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://goo.gl/EaG2Vu Software: Geometry of cycles http://moebinv.sourceforge.net/