Miscellaneous Bugs and Problems

[CH3791]

1a. Plotting the derivative of a function in the function app.
   
1b. Plotting a graph with a domain.
   
For these two cases, most of the functions would not work correctly. The ones with problems I have found include: 6 Slope, 7 Signed Area, 8 Extremum, 9 Tangent
       

2. The Define menu.
In order to make a user variable, one must use the Define Menu (shift + xtθn). The Name must be lower case and Function must be upper case. However, when you tap alpha when typing a function, it is not automatically in CAPS mode and the letters come out as lower case. This is kind of annoying as other places eg. HOME and CAS have the cases optimised correctly.
   

3. Prime messing too much with inputs.
Whenever you click on items that sit on the command line, the Prime automatically adds in a whole lot of stuff such as extra brackets and spaces. These cosmetic changes are annoying and it would still be great to have a setting to turn this off.

However, sometimes during this alteration process, the input actually turns incorrect. Two examples are listed below.

diff((x-4)*(x+9))
will become
(x-4)*(x+9)' with only the second bracket is being differentiated.

x^-1
will become
x(^-1)
The ^-1 has been converted into one unit, and it is impossible to edit the exponent itself anymore.

[DrD]

Which software version are you using?

[CH3791]

Version 10637, so should be the latest one?

[CH3791]

Ok it seems that for graphing with a domain, using a piecewise defined function solves the problems with 6 Slope, 7 Signed Area, 8 Extremum and 9 Tangent functions.

[jte]

(11-25-2016 05:10 AM)CH3791 Wrote:  1a. Plotting the derivative of a function in the function app.
...
For these two cases, most of the functions would not work correctly. The ones with problems I have found include: 6 Slope, 7 Signed Area, 8 Extremum, 9 Tangent

The Slope, Extremum, and Tangent features of the Function Plot view ask lower levels of the system to differentiate the function of interest. There are a variety of conversion issues involved.

If you go to the CAS screen and try entering
   diff(F2(X),X)
with F1 and F2 defined as you've suggested (F1(X)= X^3+3*X^2 and F2(X)= ∂(F1(X),X=X)), you'll see this (conversion) issue at a command-line level.

Similarly, an evaluation of
   ∫(F2(X),X,0,1)
in the CAS screen will show this type of conversion issue at a command-line level for integration (which the Signed Area feature of the Function app relies on).

[jte]

(11-25-2016 11:11 AM)CH3791 Wrote:  Ok it seems that for graphing with a domain, using a piecewise defined function solves the problems with 6 Slope, 7 Signed Area, 8 Extremum and 9 Tangent functions.

Yes, compare how differentiation (and integration) of F1(X) behaves in the CAS screen for F1(X)= X^2/(X>=-3 AND X<=3) vs F1(X)= PIECEWISE(X>=-3 AND X<=3,X^2).