bool CFuzzyMembershipFunction::Intersection (const CFuzzyElement& a1, const CFuzzyElement& a2, const CFuzzyElement& b1, const CFuzzyElement& b2, CFuzzyElement* pPoint)
{
if (!pPoint)
{
return false;
}
double X1 = double(a1.GetValue());
double X2 = double(a2.GetValue());
double X3 = double(b1.GetValue());
double X4 = double(b2.GetValue());
double Y1 = a1.GetMembership();
double Y2 = a2.GetMembership();
double Y3 = b1.GetMembership();
double Y4 = b2.GetMembership();
double Numerator;
double Denominator;
double Y;
double X;
double M;
double B;
double Ua;
Denominator = ((Y4 - Y3) * (X2 - X1)) - ((X4 - X3) * (Y2 - Y1));
if (fabs(Denominator) <= DBL_EPSILON)
{
// Since denominator is zero, we either have parallel or coincident lines.
return false;
}
Numerator = ((X4 - X3) * (Y1 - Y3)) - ((Y4 - Y3) * (X1 - X3));
Ua = Numerator / Denominator;
X = X1 + (Ua * (X2 - X1));
// Check line segment A
if ((long(X) < a1.GetValue()) || (a2.GetValue() < long(X)))
{
// The line intersection is not within segment A, no segment intersection.
return false;
}
// Check line segment B
if ((long(X) < b1.GetValue()) || (b2.GetValue() < long(X)))
{
// The line intersection is not within segment B, no segment intersection.
return false;
}
// Successfull segment intersection, calculate the Y value and return;
M = ((Y2 - Y1) / (X2 - X1));
B = Y1 - (M * X1);
// We must properly handle roundoff to FuzzyElement's value and still have a straight segment line.
X = RoundNearest(X);
Y = (M * X) + B;
pPoint->SetValue(long(RoundNearest(X)));
pPoint->SetMembership(Y);
return true;
}
int Round(double x, Rounding rounding) {
switch (rounding) {
case ROUND_UP : return RoundUp (x);
case ROUND_DOWN: return RoundDown (x);
default : return RoundNearest(x);
}
}