Differential Equations

[LCieParagon]

Hello everyone.

Does anyone here know an app I can install into this calculator so I can graph Differential Equations. Like similarly to the TI-89?

[Han]

Use the geometry app. Press the [Symb] key and then choose "Edit" from the menu. Now press the Toolbox key (the "B" key) and then type in plotfield so that the cursor highlights the command "plotfield." With plotfield highlighted, press the [Help] key and then select "Example" from the menu. Press [Enter] twice, then press [Plot].

Basically, you created a geometry element named GA whose definition is:

plotfield(x*sin(y),[x = ((-6) .. 6),y = ((-6) .. 6)],'normalize')

For more information, see the built-in Help for plotfield.

[LCieParagon]

(01-25-2015 04:06 PM)Han Wrote:  Use the geometry app. Press the [Symb] key and then choose "Edit" from the menu. Now press the Toolbox key (the "B" key) and then type in plotfield so that the cursor highlights the command "plotfield." With plotfield highlighted, press the [Help] key and then select "Example" from the menu. Press [Enter] twice, then press [Plot].

Basically, you created a geometry element named GA whose definition is:

plotfield(x*sin(y),[x = ((-6) .. 6),y = ((-6) .. 6)],'normalize')

For more information, see the built-in Help for plotfield.

Thanks! I can combine this with plotode and have it work to perfection. Very cool. Thanks so much!

Teaching Calculus III and ODEs will be a whole different experience now!

[Angus]

When entering an expression like the example above I have inconsistent entry behaviour. After hitting the colon inside the square brackets, the colon is not displayed in the expression. It is just displayed as a 'vector' which I would consider less readable and, yes, I was confused first. Surprisingly the format is converted to exactly the given example once confirmed. Strange and not quite understandable for me. Can someone explain why expressions are differently displayed and entered in one same app? Not talking globally, considereing the macrocosmos of home and cas.

[Snorre]

Hello Angus,

there's no colon within plotfield(x*sin(y),[x=-6..6,y=-6..6],'normalize').
Did you mean the two dots (indicating a range)?
And yes, it is indeed a vector (so, displayed differently when in input mode). If you don't like it, enter it as a list (curly braces) instead: ...{x=-6..6,y=-6..6}...

While entering it should look as in screenshot #1, after pressing [ENTER] as in #2, and finally after pressing [Plot] as in #3:
           
Greetings