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Re: decoding inbuilt function

Dear Ralph,
I will assume that there was a large dose of irony in your reply.
If a student would come to me asking "How do I take the limit of a 
function?" I would take the first calculus textbook and I will go 
through it together with the student to explain him/her the meaning of a 
limit and how to take one.
If a student would come to me asking "How do I write a code that compute 
numerically a limit?" I would just suggest to evaluate numerically the 
function for different values of the variable and see when the result 
stop changing (within to the error deemed acceptable).
If a student would come to me asking "How do I write a code that compute 
symbolically a limit?" I would suggest him/her to study a computer 
language able to create a nice parser and implement all the known 
simplification rules (I am not a computer scientist so I coulnd't go 
much further than that).
Yet here the question from the "student" seems to be "How the specific 
algorithm to take limits symbolically inside Mathematica is 
implemented?", and this is not the kind of question you can hope to get 
an answer to.


On 08/24/2011 09:15 AM, Ralph Dratman wrote:
> If a student comes to your office saying she cannot seem to understand this
> "limit" thingy, I wonder if you would wish to say, "Don't feel too bad, Ms
> Liddell. No one in our department understands limits much better than you
> do! Anyway, not enough to program a computer to do them. Only Wolfram has
> the algorithm for that."
> This seems unconscionable to me. But then, I didn't realize taking limits
> was so difficult. In order to differentiate something, obviously you have to
> take a limit. Yet I never heard of anything one couldn't manage to
> differentiate. And then having the derivative of a function would surely
> help in taking other limits involving that function. What's the big
> difficulty?
> Ralph
> On Tuesday, August 23, 2011, Murray Eisenberg<murray at>  wrote:
>> While you may get some hints about this, even from Wolfram Research
>> employees, I suspect that there's proprietary information involved!
>> On 8/22/11 6:03 AM, student wrote:
>>> hi,
>>> can any body please help me to decode the inbuilt function LIMIT in
>>> mathematica  or can any body please tell me how the inbuilt function
>>> limit works and the logic behind it
>>> please reply me soon as i really need that
>> --
>> Murray Eisenberg                     murray at
>> Mathematics&  Statistics Dept.
>> Lederle Graduate Research Tower      phone 413 549-1020 (H)
>> University of Massachusetts                413 545-2859 (W)
>> 710 North Pleasant Street            fax   413 545-1801
>> Amherst, MA 01003-9305

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