Mathc initiation/Fichiers c : c37cd
Installer et compiler ces fichiers dans votre répertoire de travail.
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c05d.c |
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/* ---------------------------------- */
/* save as c05d.c */
/* ---------------------------------- */
#include "x_hfile.h"
#include "fd.h"
/* ---------------------------------- */
int main(void)
{
double a = 0.;
double b = 2.;
double n = 2*5.;
clrscrn();
printf(" Verify with a software that f(x) >= 0 on [%.3f,%.3f]\n\n", a, b);
printf(" f : x-> %s\n\n\n\n", feq);
stop();
clrscrn();
printf(" Draw a typical vertical rectangle on the graph.\n\n\n\n");
printf(" The length of the rectangle is : %s \n", feq);
printf(" The width of the rectangle is : dx \n\n" );
printf(" The Area of the rectangle is : (%s) * dx\n", feq);
printf(" \n\n\n\n\n");
stop();
clrscrn();
printf(" If we apply \n\n\n");
printf(" (%.3f\n", b);
printf(" int( \n");
printf(" (%.3f\n\n\n", a);
printf(" to : (%s) * dx\n\n\n", feq);
printf(" We obtain a limit of sums of areas of vertical rectangles.\n\n\n");
printf(" (%.3f\n", b);
printf(" int( (%s) * dx = %.5f\n", feq, simpson(f,a,b,n));
printf(" (%.3f\n\n\n", a);
stop();
return 0;
}
/* ---------------------------------- */
Vous trouverez ci-dessous le code Gnuplot pour dessiner la fonction et un rectangle caractèristique. Ainsi que le code pour Octave pour vérifier le calcul.
Exemple de sortie écran :
Verify with a software that f(x) >= 0 on [0.000,2.000]
f : x-> x-2
Copier ce code dans gnuplot :
set zeroaxis lt 8
set grid
set object rect from 1,(1-2) to 1.05,0)
plot [ -0.0:2.0] [-2.000:1.000] (x-2)
reset
Exemple de sortie écran :
Draw a typical vertical rectangle on the graph.
The length of the rectangle is : x-2
The width of the rectangle is : dx
The Area of the rectangle is : (x-2) * dx
Press return to continue.
Exemple de sortie écran :
(2.000
int(
(0.000
to : (x-2) * dx
We obtain a limit of sums of areas of vertical rectangles.
(2.000
int( (x-2) * dx = -2.00000
(0.000
Press return to continue.
Vérifier le résultat avec Octave 5.2 : I = quad (f, a, b)
>> I = quad (@(x) (x-2), 0, 2)
I = -2