/**
* Creates a FuzzySet with a gaussian-shape such that the membership value is 1 at the leftX value
* and 0 at the rightX value. The number of points in the generated FuzzySet is determined by the
* the paramter numberOfPoints if it is acceptable (>= 5) or it is set to 5. The right point is
* actually 4 standard deviations from the left (centre) point of the gaussian curve. The right
* point and all point to its right are assumed to be zero. <br>
* The equation for the gaussian curve is: <br>
*
* <pre><code>
*
* f(x) = e ** ((-(x-c)**2)/(2*sigma))
*
* where c is the mean (centre) value and sigma is the standard deviation
*
* <br></pre></code>
*
* @param leftX the upper left x value of the gaussian-shaped curve.
* @param rightX the bottom right x value of the gaussian-shaped curve.
* @param numberOfPoints the number of points to be used when generating the gaussian-shaped
* curve.
*/
public FuzzySet generateFuzzySet(double leftX, double rightX, int numberOfPoints) {
double deltaX, x;
double sigma = (rightX - leftX) / 4.0;
double twoSigmaSquared = 2.0 * sigma * sigma;
int numPoints = returnCorrectedNumPoints(numberOfPoints);
FuzzySet fs = new FuzzySet(numPoints);
fs.numPoints = numPoints;
fs.set[0] = new SetPoint(leftX, 1.0);
deltaX = (rightX - leftX) / (numPoints - 1);
x = leftX;
for (int i = 1; i < numPoints - 1; i++) {
double membershipValue;
x += deltaX;
membershipValue = Math.pow(Math.E, -((x - leftX) * (x - leftX)) / twoSigmaSquared);
fs.set[i] = new SetPoint(x, membershipValue);
}
fs.set[numPoints - 1] = new SetPoint(rightX, 0.0);
fs.simplifySet();
return (fs);
}
/**
* Generates a FuzzySet that is a straight line (linear) from with membership value 0 on the left
* to 1 on the right.
*
* @param leftX the left most X value of the FuzzySet (where membership value is 0)
* @param rightX the right most X value of the FuzzySet (where membership value is 1)
* @param numPoints the number of points to generate for the set (if < 2 then it will be set to 2)
*/
public FuzzySet generateFuzzySet(double leftX, double rightX, int numPoints) {
if (numPoints < 2) numPoints = 2;
FuzzySet fs = new FuzzySet(numPoints);
fs.numPoints = numPoints;
if (numPoints == 2) {
fs.set[0] = new SetPoint(leftX, 0.0);
fs.set[1] = new SetPoint(rightX, 1.0);
return (fs);
} else {
double deltaX, X;
double deltaY, Y;
X = deltaX = (rightX - leftX) / (numPoints - 1);
Y = deltaY = 1.0 / (numPoints - 1);
fs.set[0] = new SetPoint(leftX, 0.0);
for (int i = 1; i < numPoints - 2; i++) {
fs.set[i] = new SetPoint(leftX + X, Y);
X += deltaX;
Y += deltaY;
}
fs.set[numPoints - 1] = new SetPoint(rightX, 1.0);
fs.simplifySet();
return (fs);
}
}
