Mathc initiation/a37b
Les fonctions f‘
[modifier | modifier le wikicode]Calculer la dérivée première.
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c00.c |
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/* ------------------------------ */
/* Save as c00.c */
/* ------------------------------ */
#include <stdio.h>
#include <math.h>
/* ------------------------------ */
double f(
double x)
{return( pow(x,2.));}
/* ------------------------------ */
char feq[] = "x**2";
/* ------------------------------ */
/* ------------------------------ */
/* ------------------------------ */
double g(
double x)
{return(pow(cos(x),2.)+sin(x)+x-3);}
/* ------------------------------ */
char geq[] = "cos(x)**2+sin(x)+x-3";
/* ------------------------------*/
/* ------------------------------*/
/* ------------------------------
f'(a) = f(a+h) - f(a-h)
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2h
------------------------------ */
double Dx_1(
double (*P_f)(double x),
double a,
double h
)
{
return( ( ((*P_f)(a+h))-((*P_f)(a-h)) ) / (2.*h) );
}
/* ------------------------------*/
int main(void)
{
double x = 2.;
double h = 0.001;
printf("\n\n");
printf(" f : -> %s\n\n",feq);
printf(" f(%.3f) = %.3f \n",x,f(x) );
printf(" f'(%.3f) = %.3f \n",x,Dx_1(f,x,h));
printf("\n\n");
printf(" g : -> %s\n\n",geq);
printf(" g(%.3f) = %.3f \n",x,g(x) );
printf(" g'(%.3f) = %.3f \n",x,Dx_1(g,x,h));
printf("\n\n Press return to continue.");
getchar();
return 0;
}
/* ------------------------------*/
/* ------------------------------*/
Exemple de sortie écran :
f : -> x**2
f(2.000) = 4.000
f'(2.000) = 4.000
g : -> cos(x)**2+sin(x)+x-3
g(2.000) = 0.082
g'(2.000) = 1.341
Press return to continue.