# Exemples de la distribution

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shadeplot.xp [ source ] [ fermer ]
```/* -*-ePiX-*- */
/* shadeplot.xp -- February 09, 2003 */
#include "epix.h"
using namespace ePiX;
double k=4;           // change width of hump
double dx = 0.05;     // width of thin shaded region
double x = 1/sqrt(k); // position of thin shaded region
double dy = 0.25;     // for vertical distance between labels; kludgey

double f(double t) { return sqrt(fabs(k)/(2*M_PI))*exp(-k*t*t); }
P pt1 = P(x, f(x)+2*dy), pt2 = P(x+dx,f(x)+dy), pt3 = P(x+3*dx,f(x));

int main()
{
unitlength("1pt");
picture(150, 150);
bounding_box(P(0,0), P(1,1));
offset(120, -320);

begin();
fill();
gray(0.4);     rect(P(x,f(x)), P(x+dx, 0));
fill(false);

arrow_camber(0.25);  arrow_fill(1);
arrow(pt1, P(0.5*(x_min+x), 0.5*f(0.5*(x_min+x))),
P(0,0), "\$F(x)=\\displaystyle\\int_a^x f(t)\\,dt\$", tr);

arrow(pt2, P(x+0.5*dx, f(x)),
P(0,0), "Area of rectangle = \$f(x)\\,dx\$", tr);

arrow(pt3, P(x+dx, 0.5*f(x+dx)),
P(0,0), "Area = \$F(x+dx)-F(x)\$", tr);

bold();
plot(f, x_min, x_max, 120);

plain(); h_axis(4); v_axis(4);

label(P(x_min,0), P(0,-5), "\$a\$", b);
label(P(x,0), P(0,-5), "\$x\$", b);
label(P(x+dx,0), P(0,-2), "\$x+dx\$", br);

end();

}
```