Re: y(x) = abs(log(x))
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In article <56uc6c$dsr@mercury.iusb.edu>, Simone P Powell
<spowell@iusb.edu> wrote:
:I was surprised when I graphed y = abs(log(x)) on the TI-85 veiw screen.
:I was also surprised that the TI-81 and 82 did a better job at graphing
:the function than the 85. The graph is asymtotic to the y-axis, and it
:appears that is what the 81 and 82 is trying to display. However, the
:TI-85 is way off the mark. Can someone tell me how accurate the TI80, 83
:or 92 does on this function?
I don't see any problem with the accuracy, really. If you look at the xres
variable on the TI-92, it has a value of 2 normally. Setting it to 1, with
a certain resolution gives about 5 pixels to .1. Thus, the value at one
pixel from zero should be |log(.02)| which is only 1.7 which is what the
TI-92 displays. If you see it blow up, that actually may be the poorer
graph. Zooming in a bit, each pixel has a value of roughly .004. Thus the
value next to zero should be 2.4 which again is roughly what the
92-displays. Just as a point of reference, for you to see the value
getting larger than 5, you need each pixel being 10^-5. This means that
even if you have around 100 pixels across on the screen you'd have 10^-3
as the x max on the graph. What I'm guessing is happening is that the
other calculators are trying to draw a line to infinity as |log(0)| might
be thought of as infinity. This gives you the what looks like the
asymptote. It's a poor graphing technique, however.
Aaron
<pre>
--
Aaron Bergman -- abergman@minerva.cis.yale.edu
<http://pantheon.yale.edu/~abergman/>
Smoke a cigarette. Slit your throat. Same concept.
</pre>
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