[OS X TeX] TKZplot2d for tikz/pgf problem.

Alain Matthes alain.matthes at mac.com
Mon May 14 12:30:36 EDT 2007

Le 14 mai 07 à 17:54, Frank STENGEL a écrit :

>
> Le 14 mai 07 à 16:19, Alain Matthes a écrit :
>
> <snip>
>
>> You need to make this
>> \tkzfctpt[type=$\bullet$]((-1),\tkzfcta){A}
>>
>> because -1 give an error (-1) is necessary
>
> As far as I know the problem stems from the fact that - is not seen
> as a unary - when the need arises (see the readme in fp.sty) Why
> not have
>
> \FPeval\x{(#2)}%

it's a fine idea, I had tested but without success but now that
works ??

>
> instead ? There will still be prblems with expressions like -(\x-exp
> (\x)).

\tkztg[color=blue,lw=.8pt,kr=0.2,kl=0.2]{\tkzfcta}({1-1/exp(1)})

works fine but the problems are different between tkztg and tksfctpt

> By the way why alternate between \x and x in the examples?

the problem arrives if xstep is used when the values of x are
between 2000 and 20000.
The values that gnuplot gives in its table are too large for
tikz

I use \def\x{(x/\xunit)} \xunit depends on xstep.

I don't know how to make this without \x

example :

\begin{tikzpicture}[scale=1.5]
\tkzinit[xmin=0,xmax=800,xstep=100,ymin=0,ymax=2000,ystep=400]
\tkzgrid[color=bistre,sub,subxstep=50,subystep=200](0,0)(800,2000)
\tkzx
\tkzy
\tkzfct[color=red,label=false,samples=100,lw=0.8pt](0..800)%
{(1./90000)*\x*\x*\x-(1./100)*\x*\x+(113./36)*\x}
\tkzpt[coord](450,400){A}
\tkzpt(800,1800){}
\tkztg[color=blue,lw=.8pt,kr=300,kl=450]{\tkzfcta}(450)
\tkztxt[style    = {draw},%
color    = black,%
bkgcolor = bistre!50,%
opacity  = 0.8]%
(300,1200)%
{$f(x)=\dfrac{1}{90000}x^3 -\dfrac{1}{{100}}x^2 +\dfrac{113}{36}x$}

\end{tikzpicture}

Alain