/** Extended trapezoid rule.
*
* This algorithm was adapted from function trapzd in
* "Numerical Recipes in C", 2nd edition,
* Press, Teukolsky, Vetterling, Flannery, chapter 4.2
*/
dvariable function_minimizer::trapzd(
dvariable (model_parameters::*func)(const dvariable&),
double a, const dvariable& b, int n)
{
double num_interval;
dvariable sum,hn,x;
static dvariable s;
static int interval;
int j;
model_parameters * ptr= (model_parameters *) mycast();
if (n == 1) {
interval=1;
return (s=0.5*(b-a)*((ptr->*func)(a)+(ptr->*func)(b)));
} else {
num_interval=interval;
hn=(b-a)/num_interval;
x=a+0.5*hn;
for (sum=0.0,j=1;j<=interval;j++,x+=hn) sum += (ptr->*func)(x);
interval *= 2;
s=0.5*(s+(b-a)*sum/num_interval);
return s;
}
}
// This function force the compilator to do push and pop with the good
static DWORD CastFloatToDW(float f)
{
return mycast(f);
}
