HP-Prime/Xcas: vector/list indexing « Next Oldest | Next Newest »

 ▼ fhub Posting Freak Posts: 1,216 Threads: 75 Joined: Jun 2011 10-27-2013, 02:55 PM I don't know if this has already been addressed here, but I just found this issue when I experimented a bit with ODEs in Xcas and the HP-Prime. There's an inconsistency between the 'Home' and CAS mode: in Home mode vector/list elements are counted starting with 1 (which is the usual way in math), but in CAS mode (and Xcas itself) the indices start with 0. :-( Argh, that's really terrible and absolutely unusual (and unacceptable) in mathematics. I know that starting array indexing with 0 is usual practice in some programming languages, but NOT in math, and I can't believe that someone could come up with this idea. In [a,b,c] there's a 1st, 2nd and 3rd element, but definitely no 'element 0'! Franz Edited: 27 Oct 2013, 2:56 p.m. ▼ Les Koller Senior Member Posts: 253 Threads: 20 Joined: Jun 2012 10-27-2013, 03:00 PM I agree. I can understand (but loathe) the need to start at 0 in a programming language, but I always write my code around this to make element 1, element 1. True, in math, this should be totally unacceptable. ▼ fhub Posting Freak Posts: 1,216 Threads: 75 Joined: Jun 2011 10-27-2013, 03:13 PM Yes, just think of a program you wrote in CAS mode which uses vector elements, and now you call this program in Home mode - you'll get a complete nonsense. Example: define v:=[a,b,c] in CAS mode Now v[1] returns b in CAS mode and a in Home mode!? Franz ▼ Les Koller Senior Member Posts: 253 Threads: 20 Joined: Jun 2012 10-27-2013, 03:18 PM Hear this HP? This HAS to be fixed. Preferably starting with ONE instead of ZERO. I can work around starting with ZERO, but it HAS to be consistent between modes on a single calculator. ▼ parisse Junior Member Posts: 38 Threads: 0 Joined: Aug 2013 10-27-2013, 03:35 PM Inside the CAS (and Xcas) you have two choices for array indices: start at 0 using [] delimiters or start at 1 using (). You just need to take care inside loop for () notation that f(j):=j+1 is ambiguous (function definition or assignation). In Xcas, you can use [[]] instead of (). ▼ Les Koller Senior Member Posts: 253 Threads: 20 Joined: Jun 2012 10-27-2013, 03:36 PM Thanks for that information. Making a note now.. fhub Posting Freak Posts: 1,216 Threads: 75 Joined: Jun 2011 10-27-2013, 04:52 PM Quote: Inside the CAS (and Xcas) you have two choices for array indices: start at 0 using [] delimiters or start at 1 using (). Thanks for the info, I didn't know that () could be used for indexing. I've just tried it and this also works in Prime's Home mode, i.e. with () the results for Home and CAS mode are the same. So unless this issue with [] has been solved, it's definitely better to only use () for list or vector indices in the Prime. Franz Edited: 27 Oct 2013, 4:53 p.m.

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