Re: A little help with a PHYSICS program
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Re: A little help with a PHYSICS program
Eric Daniel Sawicki wrote:
>
> I am haveing problems saving my results to xt1,yt1 so that I can graph the
> function. They are not strings, I used the expr()->yt1, is it OK to do
> that? Oh yeah, This is for the 92, I have a great projectile motion
Usually, using expr(whatever)->yt1 will work, providing that the
variable whose contents you are assigning is a string (you don't need
the expr() if the variable to assign is not a string) but I have had
mixed results with this on some variables/functions (in some cases, the
whole expr() string ends up being assigned to the variable). The
SURE-FIRE way to do this is to use the TI-92's string functions to
append the "->yt1" part to the expression that you want to assign, then
do the expr() to have the 92 execute the command. For instance:
"15t+42^2+2"->theExp
expr(theExp&"->yt1(t)")
The trick with using the 92's graphing variables (I usually use the
Graph command with the function rather than setting the variables, but
for some applications you just have to assign the variables) is to make
sure that the function you assign is in the variable that the 92
expects. THE 92 IS PICKIER WHEN YOU USE EVAL() THAN IT IS IN THE Y=
EDITOR.
Example: For the y(x) functions, the function has to be in x, be
constant, or evaluate to a function that is in x or is constant. For the
yt<n>(t) and xt<n>(t) functions, you have to make sure that the function
is in t, is constant, or evaluates to a function that is in t or is
constant.
If the function won't work for the context, the 92 will give you a
"Error: reserved name or system variable" message.
Hope this helps. I had some of the same problems when I first ported
some of my calculus-related TI-82 apps to the 92.
--
~~ Martin Knowles - Lightning Systems
~~ mknowles@halcyon.com
~~ Software, Hardware, Publishing/Fonts, Multimedia Design
~~ Consulting and Training
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