Re: Distance between a point and y = ax^2 + bx + c

In article <19242818.1162334487372.JavaMail.jakarta@xxxxxxxxxxxxxxxxxxxxxx>,
Magnus <maol9883@xxxxxxxxxxxxx> wrote:
Thanks for you reply :-)

Who are you talking to?

Quote the message you are replying to, in order to provide
context. Not everyone reads the newsgroup through the horrible, awful,
annoying interface of the MathForum. Click on the "Quote Original"
button when replying, and edit the text in order to include enough to
provide context, but no more than that.

Also: hit the carriage return every 60-70 characters or so. MathForum
does not provide carriage returns, which result in lines that extend
beyond the right edge of the screen. Yet another reason to avoid
reading and posting through the MathForum.


Basically what I have are a lot of points in the plane and I need to
find the closest point on an arbitrary curve y= ax^2 + bx from any of
those points. According to Maxima there is only one real root to the
equation and hence that's the only one I'm investigating. But for
some values of x0 and y0 I get only imaginary roots.

It is impossible to get only imaginary root for a cubic with real
coefficients. You are, quite simply, doing something wrong.


--
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"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes" by Bill Watterson)
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Arturo Magidin
magidin-at-member-ams-org

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