Update particle charge

main.c

@@ -41,7 +41,7 @@ int main(void)
     charge_t charges[NB_CHARGES];
     for (int i = 0; i < NB_CHARGES; i++)
     {
-        charges[i] = charge_create(rand_one() / E * (rand_one() > 0.5 ? 1 : -1), vec2_create(rand_one(), rand_one()));
+        charges[i] = charge_create(rand_one() / (rand_one() * 10 - 5), vec2_create(rand_one(), rand_one()));
     }
     draw_charges(ctxt, charges, NB_CHARGES, x0, x1, y0, y1);