[pstricks] Scaling, \psaxes, and \psplot
rossi at york.cuny.edu
rossi at york.cuny.edu
Sat Mar 12 17:51:14 CET 2005
Hello:
The file enclosed below plots the Maxwell-Boltzmann velocity probability
distribution for a sample of gas at 300 K and molar mass 40 g/mol.
But the y-axis scale is too small.
I always approached scaling for \psplot/\psaxes by the following recipe:
(value for yunit) x (actual value of y in the function) = size of graph in cm
But the probability distribution (i.e. the y-axis) is very small, and so yunit
is as large as it can be, i.e. 500 cm. And the graph of the distribution shown
on the y-axis is very shallow. I want it to look like a large camel's hump.
This can't be right. I shouldn't be using such a large value for yunit.
\psset{yunit=500cm}
What am I doing wrong? How do I plot functions that have very small values and
yet get graphs that look reasonable?
Regards,
Angelo
\documentclass[12pt,a4paper]{article}
\listfiles
\usepackage{amsmath}
\usepackage{pst-plot}
\usepackage{pstricks-add}
\begin{document}
\psset{xunit=0.01cm, yunit=500cm}
\begin{pspicture}(0,0)(1000.,0.005)
% \psgrid[griddots=10,gridlabels=0pt, subgriddiv=0]
\psaxes[Dx=100., Dy=0.00075]{->}(0,0)(1100,0.005)
\psplot[linecolor=red, plotstyle=curve, linewidth=2pt]{0.00}{1100.}{%
/e 2.718282 def
/const1 3.30 10 8 neg exp mul def
/s 10 1 exp def
/const2 6.04 10 6 neg exp mul def
const1 x x mul mul e const2 neg x x mul mul exp mul}
\end{pspicture}
\end{document}
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