I just bought a TI-89 calculator. Is there any way to use differential notation with the calculator so that I can take a total differential? For instance:
f(x,y,z)
df = @f/@x dx + @f/@y dy + @f/@z dz
I'm using the @ sign in place of the partial derivative symbol here.
I ask because this is a useful way of expressing the change in f with regard to all of its parameters. I also wonder if the TI-89 can distinguish that dx and dy can be used as variables, etc.
Thanks for the help.
I found this function out on the net that says it will give the differential form of a function, but I can't seem to get it to work on my TI-89 Titanium. Could someone give me a little help on the programming. I'm not much of a TI-BASIC programmer (not at all really).
tot_dif(u,n)
Func
Local difvar,z_,dz_,i_,grd,f_,v
varlist(right(u))v
expr("d"&when(n=1,"",string(n))&string(left(u)))z_
right(u)f_
Define grd(f,vars)=seq(ΒΌ(f,vars[i_]),i_,1,dim(vars))
seq(expr("d"&string(v[i_])),i_,1,dim(v),1)difvar
dotP(grd(f_,v),difvar)dz_
Loop
If n=1
Return z_=comDenom(expand(dz_),v)
dotP(grd(dz_,v),difvar)dz_
n-1n
EndLoop
EndFunc
Also, do I have to type this in on the keyboard on the calculator itself? I managed to open this in TI-Edit, but whenever I save it as a .89f file, TI Connect says that it's an incompatible file.
If I type it in, what character will give me that little subscript T ()?
Thanks for the help
Well I guess I managed to figure this out on my own. The problem was with TI Connect. It kept telling me that the function was incompatible, but I repaired my install, and it worked. So I'm a happy camper. If anyone else is looking for a function that gives you total differentials, let me know and I can post it.