Mathc initiation/Fichiers c : c42cc
La méthode des disques, est une méthode de calcul du volume d'un solide de révolution par intégration selon un axe «parallèle» à l'axe de révolution. [wikipedia]
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c05c.c |
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/* ---------------------------------- */
/* save as c05c.c */
/* ---------------------------------- */
#include "x_hfile.h"
#include "fc.h"
/* ---------------------------------- */
int main(void)
{
int n = 2*10;
double a = 0.2;
double b = 1.;
clrscrn();
printf(" Compute the volume V of the solid of revolution \n");
printf(" generated by revolving R about the x-axis \n\n");
printf(" Draw the region R bounded by the graph of f, the x-axis,\n");
printf(" and the vertical lines x = a and x = b \n\n");
printf(" Let f be continous on [%.3f,%.3f].\n\n", a, b);
printf(" f : x-> %s\n\n", feq);
stop();
clrscrn();
printf(" Draw a typical vertical rectangle. \n\n");
printf(" The radius of the disk : %s \n", feq);
printf(" The thickness of the disk : dx\n");
printf(" The volume of the disk : Pi (%s)**2 dx \n\n\n", feq);
printf(" Volume of a Circular disk = Pi (radius)**2 (thickness)\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 : Pi (%s)**2 dx\n\n\n", feq);
printf(" We obtain a limit of sums of volumes of disks.\n\n\n");
printf(" (%.3f\n", b);
printf(" int( Pi (%s)**2 dx = %.3f\n", feq, simpson(VCircularDisk,a,b,n));
printf(" (%.3f\n", a);
stop();
return 0;
}
/* ---------------------------------- */
/* ---------------------------------- */
Exemple de sortie écran :
Compute the volume V of the solid of revolution
generated by revolving R about the x-axis
Draw the region R bounded by the graph of f, the x-axis,
and the vertical lines x = a and x = b
Let f be continous on [0.200,1.000].
f : x-> 1./x
Press return to continue.
Dessinons avec gnuplot la fonction f :
set zeroaxis lt 8
set grid
plot [.2:1.000] [-5.000:5.000] (1./x)
reset
Exemple de sortie écran :
Draw a typical vertical rectangle.
The radius of the disk : 1./x
The thickness of the disk : dx
The volume of the disk : Pi (1./x)**2 dx
Volume of a Circular disk = Pi (radius)**2 (thickness)
Press return to continue.
Dessinons un rectangle pour construire l'équation du volume:
set zeroaxis lt 8
set grid
set object 3 rect from 0.4,0 to 0.403,(1./0.403)
plot [.2:1.000] [-5.000:5.000] (1./x),\
-(1./x)
reset
Exemple de sortie écran :
If we apply
(1.000
int(
(0.200
to : Pi (1./x)**2 dx
We obtain a limit of sums of volumes of disks.
(1.000
int( Pi (1./x)**2 dx = 12.569
(0.200
Press return to continue.
Vérifier le résultat avec Octave 5.2 : I = quad (f, a, b)
>> I = quad (@(x) pi*((1./x).*(1./x)),.2,1)
I = 12.566