[CAS] Potential Bug with given (|). [SOLVED]

[Nigel (UK)]

(10-30-2016 05:03 PM)Mark Hardman Wrote:  This would appear to be by design. The CAS system is converting the compound given statement into the following explicit assumptions:

assume(x>0) -> x
additionally(x<10) -> x

This creates the following permanent assumptions on x:

about(x) -> assume[[],[line[0,10]],[0,10]]

Which provides the correct solution:

solve((x^2-8) = 0,x) -> {2*√2}

To avoid future use of the assumptions on x, they must be purged:

purge(x) -> assume[[],[line[0,10]],[0,10]]
about(x) -> x

Mark Hardman

If this is intentional I think it is a bad idea. I think of the "|" operator as making a temporary assignment to a variable or applying a temporary restriction and I suspect that most people would feel this way too.

TI CAS calculators have got a menu function that clears single-character variable names (a-z). It would be a good idea to advise users to implement their own such function on the Prime, and to use it regularly! Thanks to CH3791 for pointing out this potential pitfall.

Nigel (UK)