On Feb 12, 10:07 am, bill purvis <[EMAIL PROTECTED]> wrote:
> I wanted to make a plot of x^3+y^3=1729 (the well-known taxicab problem).
> I'm sure there are better ways of acieving this but I opted for a naive
> approach:
>
> {{{
> def sng(x):
> if x < 0:
> return -1
> return 1
>
> def f(x):
> y3 = 1729 - x^3
> return sgn(y3) * abs(y3)^(1/3)
>
> }}}
>
> {{{
> c = parametric_plot((x,f(x)),-15,15)
> c.show()
>
> }}}
>
> (I want to add other things to the plot).
> However, when I run this in the notebook, the plot has a cusp at x=12+
> and behaves as if the sgn(x) has been taken as +1. I tried evaluating
> f(x) at 12 and 13 and the result changes sign as I'd expect.
> Am I doing something totally stupid or is there a bug here?
>
> Bill
> (still running 2.10.1.rc3 on Linux, Ubuntu 7.10 on a Toshiba Equium laptop)
> --
> +---------------------------------------+
> | Bill Purvis, Amateur Mathematician |
> | email: [EMAIL PROTECTED] |
> | http://bil.members.beeb.net |
> +---------------------------------------+
Still no response to this problem, either....
Bill
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