Flute acoustics: measurement, modelling and design - School of ...

APPENDIX B. PROGRAM LISTINGS 254
2.0*((sqrt((y0 + 3.0 - a)/c
+ (b/(2.0*c))*(b/(2.0*c))) - (b/(2.0*c))) - x0);
}
else {
ext->type = MAXIMUM;
/* determine analytical maximum from parabola fit */
x0 = -1.0*(b/(2.0*c));
y0 = a + b*x0 + c*x0*x0;
if(weight) {
/* find frequency of absolute maximum in data vector */
maxf = highest(points);
numext = numExtrema(points, MAXIMUM);
/* if only one maximum in set, heavily weight to absolute
maximum */
if(numext == 1) {
ext->f = (x0*maxf)/(0.95*x0 + 0.05*maxf);
}
/* otherwise, moderately weight towards absolute maximum */
else {
ext->f = (x0*maxf)/(0.75*x0 + 0.25*maxf);
}
}
/* if weight is false, use fit to determine f */
else
ext->f = x0;
/* construct maximum
impedance is parabola maximum
bandwidth and Q factor is 3dB span of parabola */
ext->Z = y0;
ext->B =
2.0*((sqrt((y0 - 3.0 - a)/c
+ (b/(2.0*c))*(b/(2.0*c))) - (b/(2.0*c))) - x0);
}
}
return ext;
int progressPoints(Vector points, Vector allpoints, int index) {
Point p = (Point)malloc(sizeof(*p));
/* read points if data still in file */
if(index < sizeVector(allpoints)) {
*p = *((Point)elementAt(allpoints, index));
/* remove oldest point and add newly read point */
popFront(points);
addElement(points, p);
return 1;
}
/* otherwise end of data reached */
else
return 0;
}
int numExtrema(Vector points, minmax type) {