Re: Why does the TI-85 do...


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Re: Why does the TI-85 do...



>Hi everybody, does some of you know how to integrate
>
>e^-(0.5x^2) from -infinity to t by hand or by calculator?
>
>When I type in fnInt(e^(-0.5x^2),x,-e99,t) I get 0 for every value of t.
>Why?
>My calculator is in floating point mode, tolerance set to e-5 and delta to
>0.01. My ROM version is 8.0 however the problem occurs on ROM 10.0 machines
>too.
........
>
>Kind regards Kasper Vibe Grevsen, Denmark

I think the problem is that you are starting at the "small end", where the
integrand basically vanishes.  Because the function is symmetric, this should
be the same as  fnint(e^(-0.5x^2),x,-t,e99).  There would seem to be very
little reason to go out anywhere near so far, anyway, as the integrand is
already negligibly small for x=100 or 1000.  Why add up all those zeros?

RWW Taylor
National Technical Institute for the Deaf
Rochester Institute of Technology
Rochester NY 14623

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