Bugs about simpilfy function in the cas

[wangchong01]

(09-11-2017 11:32 AM)DrD Wrote:  The CAS also will return "simplified" results even if the Simplify setting is "None."

For an example, you can experiment with the following function, (especially interesting to calculus students), by cycling through the CAS settings for Simplify: {None, Minimum, Maximum}:

[CAS] Exact[✔]
factor(((x^2-4)/(x^2+x-6))) ==> (x+2)/(x+3)

[CAS] Exact[ ]
factor(((x^2-4)/(x^2+x-6))) ==> (x-2)*(x+2)/((x-2)*(x+3))

The domain is not continuous, (at x=2), but the factor (x-2) gets masked for all simplify settings, (with Exact checked). There are work-a rounds:

factor(x^2-4) / factor(x^2 + x -6) ==> (x-2)*(x+2)/((x-2)*(x+3))

or uncheck the Exact setting:
factor(((x^2-4)/(x^2+x-6))) ==> (x-2.)*(x+2.)/((x-2.)*(x+3.))

Shouldn't a Simplify setting of "None" fully factorize the functions, and not mask the (x-2) term? Including all the singularities is important, for this kind of example. Attention to the subject matter at the student level can be difficult enough, and requiring special settings, or command variations, only diverts attention from the specific learning environment.

The simplify will ignore approx expressions such as (1.1*x)/x. You can you normal() to "simplify" the function and then simplify().