VI

EMACS

CVS

GIT

L^ATEX

ICALENDAR

ROBOTS

CORBA

QEMU

MAKEFILE

AUTOTOOLS

GNUPLOT

SCREEN

GRUB

MAO

VHS

ISO

Home

Up

Contents

• 1 Introduction
• 2 Exemple 1
• 3 Exemple 2
• 4 Approximation (fit)

1 Introduction

# apt-get install gnuplot gnuplot-doc

Sous emacs : M-x info puis m gnuplot

2 Exemple 1

$ x=0; while [ $x -lt 10 ]; do y=$(echo "e($x)" | bc -l); echo -e "$x\t$y"; x=$[$x+1]; done > exp.dat

$ gnuplot
> plot "exp.dat" with line,"exp.dat" with impulses
> ^D

$ gnuplot << EOF > test.png
set terminal png
plot "exp.dat" with line,"exp.dat" with impulses
EOF

$ qiv test.png

3 Exemple 2

• Données (sous bash)

  min=-5
  max=5
  step=0.1
  
  # cos
  x=$min; \
  while [ $(echo "$x<=$max" | bc) -eq 1 ]; do \
   y=$(echo "c($x)" | bc -l); \
   echo -e "$x\t$y"; \
   x=$(echo $x+$step | bc); \
  done > cos.dat
  
  # sin
  x=$min; \
  while [ $(echo "$x<=$max" | bc) -eq 1 ]; do \
   y=$(echo "s($x)" | bc -l); \
   echo -e "$x\t$y"; \
   x=$(echo $x+$step | bc); \
  done > sin.dat
  
  # arctan
  x=$min; \
  while [ $(echo "$x<=$max" | bc) -eq 1 ]; do \
   y=$(echo "a($x)" | bc -l); \
   echo -e "$x\t$y"; \
   x=$(echo $x+$step | bc); \
  done > arc.dat
  

• Simple tracé

  $ gnuplot << EOF
  set terminal png
  set output 'test.png'
  plot "cos.dat" with line, \
       "sin.dat" with line, \
       "arc.dat" with line
  EOF
  
  $ qiv test.png
  

• Tracé quelque-peu amélioré

  $ gnuplot << EOF
  set output 'test.png'
  set terminal png size 1000,500 
  set title "trigonometrie\ncos, sin et arctan";
  set xlabel "degres";
  set ylabel "amplitude";
  set grid
  plot "cos.dat" with line, \
       "sin.dat" with line, \
       "arc.dat" with line
  EOF
  
  $ qiv test.png
  

4 Approximation (fit)

• test.dat

  0 0 
  1 2
  2 4
  3 8
  4 16
  5 32
  6 64
  7 128
  

• test.plot

  set terminal png
  set output 'test.png'
  set xrange [0:10]
  set yrange [0:100]
  
  f(x) = a1 + b1*x + c1*x**2
  fit [0:5346] f(x) "test.dat" via a1,b1,c1
  
  g(x) = a2 * exp (x*b2)
  fit [0:5346] g(x) "test.dat" via a2,b2
  
  plot "test.dat", f(x), g(x)
  

• Tracé de 2 courbes : polynomiale et exponentielle

  $ gnuplot test.plot
  $ qiv test.png
  

Home

Up

This document is also available in PDF and PostScript format.