TI89 Miscellaneous

Functions

Exact differential equation test
Angle of parallelism for a given distance

Exact differential equation test

            partials(m,n)

            Prgm

            @m(x,y),n(x,y)

            ClrIO

            @ToDo: allow them to differ by constants

            If d(m,y)=d(n,x) Then

             Pause d(m,y)

             Pause [["M:"&string(expand(
∫(m,x)))&"+c(y)"]["N:"&string
(expand(∫(n,y)))&"+c(x)"]]

            Else

             Disp "Not exact"

            EndIf

            EndPrgm

Angle of parallelism for a given distance

            ang(dist)

            Func

            @angle of || for a given

            distance

            Return 2*tan-1(e^(-dist))

            EndFunc