示例#1
0
 /// <summary>Gets the (complex) roots of a specified polynomial of degree up to 4.
 /// </summary>
 /// <param name="absoluteCoefficient">The absolute coefficient.</param>
 /// <param name="firstOrderCoefficient">The first order coefficient.</param>
 /// <param name="secondOrderCoefficient">The second order coefficient.</param>
 /// <param name="thirdOrderCoefficient">The third order coefficient.</param>
 /// <param name="fourthOrderCoefficient">The fourth order coefficient.</param>
 /// <param name="firstRoot">The first root (output).</param>
 /// <param name="secondRoot">The second root (output).</param>
 /// <param name="thirdRoot">The third root (output).</param>
 /// <param name="fourthRoot">The fourth root (output).</param>
 /// <returns>The order of the polynomial represented by the coefficients, i.e. the number of roots.</returns>
 public static int GetRoots(double absoluteCoefficient, double firstOrderCoefficient, double secondOrderCoefficient, double thirdOrderCoefficient, double fourthOrderCoefficient, out System.Numerics.Complex firstRoot, out System.Numerics.Complex secondRoot, out System.Numerics.Complex thirdRoot, out System.Numerics.Complex fourthRoot)
 {
     if (fourthOrderCoefficient != 0.0) // degree 4
     {
         RealDegreeFourPolynomial.GetRoots(absoluteCoefficient, firstOrderCoefficient, secondOrderCoefficient, thirdOrderCoefficient, fourthOrderCoefficient, out firstRoot, out secondRoot, out thirdRoot, out fourthRoot);
         return(4);
     }
     if (thirdOrderCoefficient != 0.0)  // degree 3
     {
         RealDegreeThreePolynomial.GetRoots(absoluteCoefficient, firstOrderCoefficient, secondOrderCoefficient, thirdOrderCoefficient, out firstRoot, out secondRoot, out thirdRoot);
         fourthRoot = new System.Numerics.Complex(Double.NaN, Double.NaN);
         return(3);
     }
     if (secondOrderCoefficient != 0.0)   // degree 2
     {
         RealDegreeTwoPolynomial.GetRoots(absoluteCoefficient, firstOrderCoefficient, secondOrderCoefficient, out firstRoot, out secondRoot);
         thirdRoot = fourthRoot = new System.Numerics.Complex(Double.NaN, Double.NaN);
         return(2);
     }
     else if (firstOrderCoefficient != 0.0)                                     // degree 1
     {
         firstRoot  = unchecked (-absoluteCoefficient / firstOrderCoefficient); // the highest coefficient is always != 0.0, but maybe near 0.0
         secondRoot = thirdRoot = fourthRoot = new System.Numerics.Complex(Double.NaN, Double.NaN);
         return(1);
     }
     else  // degree 0
     {
         firstRoot = secondRoot = thirdRoot = fourthRoot = new System.Numerics.Complex(Double.NaN, Double.NaN);
         return(0);
     }
 }