Improper integral

[Onkel Otto]

(06-14-2014 09:40 AM)alexzkter Wrote:  Is it the way it's meant to be? I mean, if you change a setting on CAS, shouldn't it just affect the CAS mode?

+ 1

I really do not like this kind of inconsistencies.

[cutterjohn]

This made me curious, so I dug out the FX-CP400 which spat out:
((-5*(-1)^(4/5))/4) + 20
which converting to decimal result:
21.01127124-0.7347315654i

[EDIT]
classpad was in complex mode.

...also realized that the screen on the cp400 just doesn't seem to be very good, which in addition to getting the prime about the same time may help explain why I've avoided using it much... that and it's interface is clunky as hell... and it's comparatively slow...
[/EDIT]

[Joe Horn]

(06-14-2014 10:23 AM)Onkel Otto Wrote:  

(06-14-2014 09:40 AM)alexzkter Wrote:  Is it the way it's meant to be? I mean, if you change a setting on CAS, shouldn't it just affect the CAS mode?

+ 1

I really do not like this kind of inconsistencies.

No no no, it's not inconsistent at all. One of the main benefits of the "Change apparent integers to exact integers" CAS setting is that it lets you use CAS functions, with CAS accuracy, from Home (and in non-CAS programs).

Why? Here's why. In CAS, you can specify whether the input is an integer, or a whole real, by omitting or including a decimal point, respectively. For example, try the following with "sqrt" spelled out (not using the √ key):

CAS: sqrt(8) --> 2*√2
CAS: sqrt(8.) --> 2.82842712475

Nice, right? Ah, but Home does not make this distinction between integers and whole reals. In fact, Home doesn't support the integer object type at all; Home passes all numbers to CAS as reals. So how can the user force CAS functions, when called from home, to treat whole numbers as integers?

Answer: By setting the "Change apparent integers to exact integers" flag. That's what it's for.

Home: sqrt(8) = sqrt(8.) = 2.82842712475 if that flag is clear.
Home: sqrt(8) = sqrt(8.) = 2*√2 if that flag is set.

If that setting did not exist, people would be bellyaching about not being able to use CAS functions in Home the way they want to. So that flag was added... so that people CAN use CAS functions in Home and in programs the way they work in CAS if they want to. This is a Good Thing.

The only objection I can think of is, "But what good is that information to programmers, when that flag is not programmable???" To which I answer: If you want your program to use the integer object type and reals without needing to worry about that flag, then write CAS programs.

[Onkel Otto]

The Flag affects the output in Home.
So the option to Check/Uncheck is to be expected in the settings of Home
and not in the CAS setup.
This is the inconsistency.

[alexzkter]

(06-17-2014 10:40 AM)Onkel Otto Wrote:  The Flag affects the output in Home.
So the option to Check/Uncheck is to be expected in the settings of Home
and not in the CAS setup.
This is the inconsistency.

+
That was actually my concern. I wonder if even what Joe explained is on the user guide.

[Joe Horn]

(06-17-2014 01:29 PM)alexzkter Wrote:  

(06-17-2014 10:40 AM)Onkel Otto Wrote:  The Flag affects the output in Home.
So the option to Check/Uncheck is to be expected in the settings of Home
and not in the CAS setup.
This is the inconsistency.

+
That was actually my concern. I wonder if even what Joe explained is on the user guide.

Yes, the current edition of the user guide explains that checkbox setting on page 56:

"If checked, any real number equivalent to an integer in a non-CAS environment will be converted to an integer in the CAS. (Real numbers not equivalent to integers are treated as real numbers in CAS whether or not this option is selected.)" [emphasis added by me]

Please note that "non-CAS environment" means more than just Home view. It also includes non-CAS programs, functions in the graphing apps, formulae in the Spreadsheet app, etc.

Bottom line: it's not only about Home, but it IS only about CAS functions, so that's why it's in the CAS Settings, not the Home Settings. No inconsistency.