Re: Hybrid functions on the ti-85.
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Re: Hybrid functions on the ti-85.
The only way that I know for graphing piecewise functions or restricting
the domain of a function is to use the following trick I made up:
(disclaimer: I'm sure that maybe other people have thought of this too)
1. enclose your function in parenthesis
2. multiply the function by the rannge you want. for example:
y1=(x^2 + 2x + 1)(x>2)(x<6)
the (x>2) and (x<6) each evaluate to 1 if they're true and 0 if they're
false. So the expression above can be read as y=f(x) AND x>2 AND x<6.
When you graph this function, the ti will plot f(x) if both equality
expressions are true (in this case 2<x<6 ), and 0 for values of x that
make one or more of the range expressions false. I think this will work
on all ti graphing calculators.
You can also graph F(x) with an OR. For example, if the range of f(x)
is X<-2 OR x>2 , type this:
y2=(x^2 -9) ((x<-2) or (x>2))
or type this if your calculator doesn't do OR (like my old ti81):
y2=(x^2-9) ( ((x<-2) + (x>2)) >0)
either way, the idea is to multiply your function by a range expression
that equals either 1 or 0 when you want it to. (be careful if you use
the + as an OR operator: if both range expressions are true at the same
time, your function could be multiplied by TWO if you're no careful. In
the above expression, adding the >0 insures that the whole mess
multiplying f(x) will evaluate to 1 even if the ranges overlap.) You can
also use other ti functions like MIN and MAX to help you restrict your
function.
Note: you should graph in DOT mode, or else you'll get what appears to
be a vertical asemtote on your range boundaries.
-Jonathan
References: