/* Split into several TFs with denominators of linear or quadratic order. NOTE, DENOMINATOR
MUST START WITH COEFFICENT 1. NOTE, DOESN'T WORK IF MULTIPLE LINEAR VALUES */
public TransferFunction[] partialFractions() {
Polynomial[] factors = den.factorise();
for (int i = 0; i < factors.length; i++) {
System.out.println(factors[i]);
}
// Handle partial fractions based on denominator type
int len = factors.length;
if (len > 3) {
System.out.println("can't do partial fractions, denominator is too big.");
}
// Three linear components
if (len == 3) {
// Check
for (int i = 0; i < 3; i++) {
if (factors[i].getDegree() > 1) {
System.out.println("can't do partial fractions, denominator is too big.");
}
}
// Get the linear coefficients a,b,c
double a = factors[0].getCoefficients()[0];
double b = factors[1].getCoefficients()[0];
double c = factors[2].getCoefficients()[0];
// Get the numerator coefficients A,B,C
double[] coef_num = num.getCoefficients();
double A = 0;
double B = 0;
double C = 0;
if (coef_num.length >= 3) A = coef_num[2];
if (coef_num.length >= 2) B = coef_num[1];
if (coef_num.length >= 1) C = coef_num[0];
double[] num2 = new double[1];
double[] num1 = new double[1];
double[] num0 = new double[1];
num2[0] = C / ((a - c) * (c - b));
num1[0] = (B - num2[0] * (a + c)) / (a + b);
num0[0] = A - num1[0] - num0[0];
TransferFunction tf0 = new TransferFunction(new Polynomial(num0), factors[0]);
TransferFunction tf1 = new TransferFunction(new Polynomial(num1), factors[1]);
TransferFunction tf2 = new TransferFunction(new Polynomial(num2), factors[2]);
System.out.println(tf0);
System.out.println(tf1);
System.out.println(tf2);
TransferFunction[] result = new TransferFunction[3];
result[0] = tf0;
result[1] = tf1;
result[2] = tf2;
}
// Linear and quadratic, or linear and linear
if (len == 2) {
// Linear and quadratic
if (factors[1].getDegree() == 2) {
// Get the linear coefficients a, and quadratic coefficients c,d (scaled by b)
double a = factors[0].getCoefficients()[0];
double b = factors[1].getCoefficients()[2];
double c = factors[1].getCoefficients()[1] / b;
double d = factors[1].getCoefficients()[0] / b;
// Get the numerator coefficients A,B,C
double[] coef_num = num.getCoefficients();
double A = 0;
double B = 0;
double C = 0;
if (coef_num.length >= 3) A = coef_num[2] / b;
if (coef_num.length >= 2) B = coef_num[1] / b;
if (coef_num.length >= 1) C = coef_num[0] / b;
double[] num1 = new double[2];
double[] num0 = new double[1];
num1[0] = C / (d / (1 - c) + a);
num1[1] = B - num1[0] / (1 - c);
num0[0] = A - num1[1];
TransferFunction tf0 = new TransferFunction(new Polynomial(num0), factors[0]);
TransferFunction tf1 = new TransferFunction(new Polynomial(num1), factors[1].divide(b));
System.out.println(tf0);
System.out.println(tf1);
}
}
return null;
}
