I first need to connect seasvpn.seas.wustl.edu.
I assume I can do it now. I can't test it due to firewall at work.
I'll let you know if I can't log in.
Kari
> If I were teaching this I would first build some terms of the series
> manually.
>
> Put on the board (or in a J session displayed on a screen in front of the
> class):
> 1 1
> Ask the class what is the sum of the last two numbers. Hopefully, someone
> says "2". Then write "2" after the numbers on the board.
> 1 1 2
> Ask again what the sum of the last two digits is. Answer: "3"
> 1 1 2 3
>
> Repeat a couple of more times getting something like the following and
> give
> it a name:
> y=:1 1 2 3 5 8
> This demonstrates what the series is and how to build it.
> Now ask the class how to get the last two digits of y. (This is assuming
> you have already introduced some J expressions like {. and +/ to the class
> earlier.) In J that would be:
> _2{.y
> 5 8
> Now ask how to add the digits in J:
> +/5 8
>
> Then put it together:
> +/_2{.y
> 13
>
> Then concatenate it to the list built so far:
> y,+/_2{.y
> 1 1 2 3 5 8 13
>
> Now define a verb to do this, maybe called "f". Simply wrap what you have
> above giving:
> f =: 3 : 'y,+/_2{.y'
> If you are doing this on a computer it would be easy to simply add the
> characters around the expression already used.
>
> Then go back to the beginning:
> f 1 1
> 1 1 2
>
> Then add an "f":
> f f 1 1
> 1 1 2 3
>
> And repeat for a while to something like:
> f f f f f 1 1
> 1 1 2 3 5 8 13
>
> power=:2 : 'v^:m y' NB. To repeat verb v m times
> A conjunction "power", which you don't have to explain how it works to the
> class, simply have it already defined.
>
> Now use it with f:
> f 1 1
> 1 1 2
> 1 power f 1 1
> 1 1 2
> 2 power f 1 1
> 1 1 2 3
> 5 power f 1 1
> 1 1 2 3 5 8 13
> 12 power f 1 1
> 1 1 2 3 5 8 13 21 34 55 89 144 233 377
>
> It might be fun to ask them what the 100th fibonacci number is.
> {:98 power f 1 1x
> 354224848179261915075
> Then explain that since you started with 2 terms already you only needed
> to
> do it 98 more times.
>
>
> Okay, so this is not how to program in the tradition of C or whatever, but
> it is J-like and should be easy for students to see what's happening. A
> way
> for them to approach solving problems themselves by testing as they go.
> ----------------------------------------------------------------------
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