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.

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.

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

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.

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 ().

Thanks for that information. Making a note now..

Quote:

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Inside the CAS (and Xcas) you have two choices for array indices: start at 0 using [] delimiters or start at 1 using ().

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Franz

Edited: 27 Oct 2013, 4:53 p.m.