Absolute value: sometimes CAS is very clever, sometimes not!

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Absolute value: sometimes CAS is very clever, sometimes not!

09-09-2018, 09:56 AM (This post was last modified: 09-09-2018 09:58 AM by ijabbott.)

Post: #25

ijabbott Offline

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RE: Absolute value: sometimes CAS is very clever, sometimes not!

Here are a few one liners to illustrate the problem:

domain(ln(x),x) →x>0
simplify(domain(ln(x),x))→x>0
domain(1/x,x)→x≠0
simplify(domain(1/x,x))→1 «???»

Specifically, the bad simplification on line 4 is the problem.

Perhaps the domain on line 3 could be expressed as x<0 OR x>0 to avoid the bad simplification?

— Ian Abbott

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Messages In This Thread

Absolute value: sometimes CAS is very clever, sometimes not! - jfdHP - 09-06-2018, 06:14 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - Tim Wessman - 09-07-2018, 12:23 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - toml_12953 - 09-07-2018, 02:27 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-07-2018, 05:33 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - CyberAngel - 09-07-2018, 05:55 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-07-2018, 07:06 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - CyberAngel - 09-07-2018, 11:26 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-07-2018, 08:57 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - Komanguy - 09-07-2018, 04:30 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - jfdHP - 09-07-2018, 09:06 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - compsystems - 09-07-2018, 06:34 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - CyberAngel - 09-07-2018, 06:37 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - compsystems - 09-07-2018, 06:46 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 03:37 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - Joe Horn - 09-08-2018, 04:38 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 05:32 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-08-2018, 06:05 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 09:43 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 10:43 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-08-2018, 10:52 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - compsystems - 09-08-2018, 03:28 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 04:06 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-08-2018, 11:11 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-09-2018, 06:19 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-09-2018 09:56 AM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-09-2018, 01:45 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - ijabbott - 09-09-2018, 07:21 PM

RE: Absolute value: sometimes CAS is very clever, sometimes not! - parisse - 09-09-2018, 07:57 PM

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