TI 89 program missing a parenthesis

[breebreebran]

I'm trying to write a program to find midpoint and distance.
And here's what I have.

Prompt dist
If dist=1 then
Prompt x,y,x2,y2
√((x2-x)^2+(y2-y)^2)→d
Disp d
Else
Prompt xx1,xx2,yy1,yy2
(xx1+xx2)/2→a
(yy1+yy2)/2→b
Disp a,b
Endif
Endprgm

When I try to run this program it says I am missing a parenthesis somewhere.
And I had modified the code before. I don't remember how. But when I did that it said that the variable was already reserved or something like that.

 

[Greg Bernhardt]

Here is a list of reserved variables for the ti89
http://www.technicalc.org/tiplist/en/files/pdf/tips/tip1_3.pdf

 

[nathanthegreat]

First thing: unless you need the variables that aren't standard like x or y outside of the program, I would make them local. Otherwise you'll have a mess of variables if you keep using new ones. just do "Local x2,y2,..." for all of the non-standard variables.

Second thing: your program is missing two important things which are "programname()" in the first line and "Prgm" in the second line. Did you just forget to type these?

Third thing: I just typed the code into my 89 exactly as you have it written out (only I put the local in so I didn't get the variables stored on my calculator) and got an error that I had an invalid variable in my local definition. Looking over the variables, I thought y2 was the most likely culprit because the calculator uses y a lot in graphing as its variable. I changed it to yy and then the program executed perfectly. So just change the y2 to yy or any other name and you should be set.

All of that said, it's a very ugly program, no offense to you. The variable names are too long and it isn't clear what they're for. Also, you don't even need the xx1, xx2, yy1, and yy2 because you will never use both parts of the if statement in one execution of the program, so you can just prompt for x, y, x1, and yy. But, if you're interested, i could show you how I would write the program to make it much more visually appealing, more functional, and easier to interpret the results. In short, you don't even use the I/O screen (where prompt and disp go) and you use dialog boxes instead. The coding is slightly trickier and you have to work with strings, but I think you would be much happier with the results. If you are interested, let me know and I can type out the code for you.

-Nathan