psplot and this function

[Denis Girou]

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>>>>> "Bastian.Kruse" == KRUSE BASTIAN <W3KRUS01 at stud.uni-passau.de> writes:

    Bastian.Kruse> i wanted to plot this function
    Bastian.Kruse> \frac{0.08*e^{-x}-(1-0.08)^16*0.08*e^{-x*17)}{1-(1-0.08)*e{-x}}
    Bastian.Kruse> Guess I have to use 2.71828 instead of e, cause postscript doesn at t 
    Bastian.Kruse> know fhis.
    Bastian.Kruse> I have trouble with the e^{-x}. The minus makes me sick ? What at s the 
    Bastian.Kruse> correct input?

  PSTricks just use here the PostScript programming language. So, you must refer
here to a PostScript book. The reference one is: "PostScript Reference
Manual", Addison-Wesley. You can found some summaries and syntax descriptions
online. For instance, for the arithmetic operators you need here ("neg" and
"exp"), you can look at:

http://ugrad.math.ubc.ca/localdoc/Flat/math-ref.html

or:

http://www.cs.indiana.edu/docproject/programming/postscript/operators.html

---
exp
base exponent exp value 
This operator returns the value of base raised to the exponent power. 
---
neg
value1 neg - value1 
This operator returns -value1.
---

    Bastian.Kruse> How does postscipt know when the counter ends and the denominator 
    Bastian.Kruse> starts?

  This is a postfix language using the so-called Polish notation (not
"natural" for humans, but easy to handle by an automatic process like
a computer program). Denominator end when the heap is empty.

  So what you are looking for is something like that (you must check it...):

\documentclass{article}

\usepackage{pst-plot}

\pagestyle{empty}

\begin{document}

\begin{center}
  \begin{displaymath}
    f(x)=\frac{0.08*e^{-x}-(1-0.08)^{16}*0.08*e^{-x*17}}{1-(1-0.08)*e^{-x}}
  \end{displaymath}

  \begin{pspicture}(-1.5,-0.5)(5,5)
    \psaxes[Ox=-1,tickstyle=top,axesstyle=frame](-1,0)(5,5)
    \psplot{-0.2}{5}{0.08 2.71828 x neg exp mul             % 0.08*e^{-x}
                     1 0.08 sub 16 exp 0.08 mul             % (1-0.08)^{16}*0.08
                     2.71828 x neg 17 mul exp               % e^{-x*17)
                     mul sub
                     1 1 0.08 sub 2.71828 x neg exp mul sub % 1-(1-0.08)*e^{-x}
                     div}
  \end{pspicture}
\end{center}

\end{document}

D.G.

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