Class MiscMathsFunctions

java.lang.Object
solvers.utilities.MiscMathsFunctions
public class MiscMathsFunctions extends Object
This class implements several basic math functions, low-level fast memory copies, matrix type changes, memory usage calculations and printing operations. Its methods are used throughout the program, therefore it was best to gather them all here.
Author:
Michail Makaronidis, 2010

  • Method Details

    • isPowerOf2

      public static boolean isPowerOf2(int n)
      Checks if specified number is power of 2 using bitwise operators.
      Parameters:
      n - The number to check.
      Returns:
      Boolean indicating if n is a power of 2.

    • binomialCoefficient

      public static int binomialCoefficient(int n, int k)
      This method calculates the binomial coefficient C(n, k) ("n choose k")
      Parameters:
      n - The first number
      k - The second number
      Returns:
      The binomial coefficient

    • computeFactorials

      public static Map<Integer, BigRational> computeFactorials(int n)
      Computes the factorials up to a given number and returns them as a Map<Integer,BigRational>.
      Parameters:
      n - The number up to which the factorials are computed
      Returns:
      The Map<Integer,BigRational> containing the computed values

    • computeFactorialsAsBigDecimal

      public static Map<Integer, BigDecimal> computeFactorialsAsBigDecimal(int n)
      Computes the factorials up to a given number and returns them as a Map<Integer,BigDecimal>.
      Parameters:
      n - The number up to which the factorials are computed
      Returns:
      The Map<Integer,BigDecimal> containing the computed values

    • computeFactorial

      public static BigRational computeFactorial(int n)
      Computes the factorial for a given number and returns the result as a BigRational.
      Parameters:
      n - The number to calculate the factorial for.
      Returns:
      The result as a BigRational.

    • computeFactorialAsBigDecimal

      public static BigDecimal computeFactorialAsBigDecimal(int n)
      Computes the factorial for a given number and returns the result as a BigDecimal.
      Parameters:
      n - The number to calculate the factorial for.
      Returns:
      The result as a BigDecimal.

    • printMatrix

      public static void printMatrix(int[][] A)
      Prints a 2-dimensional matrix
      Parameters:
      A - A 2-dimensional matrix of ints

    • printMatrix

      public static void printMatrix(BigRational[][] A)
      Prints a 2-dimensional matrix
      Parameters:
      A - A 2-dimensional matrix of BigRationals

    • printPrettyMatrix

      public static void printPrettyMatrix(BigRational[][] A)
      Prints a 2-dimensional matrix of BigRationals as doubles.
      Parameters:
      A - A 2-dimensional matrix of BigRationals

    • printMatrix

      public static void printMatrix(int[] A)
      Prints a 1-dimensional matrix.
      Parameters:
      A - A 1-dimensional matrix of ints

    • printMatrix

      public static void printMatrix(BigRational[] A)
      Prints a 1-dimensional matrix.
      Parameters:
      A - A 1-dimensional matrix of BigRationals

    • printPrettyMatrix

      public static void printPrettyMatrix(BigRational[] A)
      Prints a 1-dimensional matrix of BigRationals as doubles.
      Parameters:
      A - A 1-dimensional matrix of BigRationals

    • createBigRationalArray

      public static BigRational[] createBigRationalArray(int[] s)
      Transforms an array of ints to an array of BigRationals.
      Parameters:
      s - The source array of ints
      Returns:
      The resulting array of BigRationals

    • createBigRationalArray

      public static BigRational[][] createBigRationalArray(int[][] d)
      Transforms an array of ints to an array of BigRationals.
      Parameters:
      d - The source array of ints
      Returns:
      The resulting array of BigRationals

    • matrixVectorMultiply

      public static BigRational[] matrixVectorMultiply(BigRational[][] A, BigRational[] v)
      Multiplies a two-dimensional matrix of BigRationals with a one-dimensional one. It does not perform a generic multiplication, but it rather checks for linear system inconsistencies as well.
      Parameters:
      A - The two-dimensional matrix
      v - The one-dimensional matrix
      Returns:
      The multiplication result

    • matrixVectorMultiplyJ

      public static BigRational[] matrixVectorMultiplyJ(BigRational[][] A, BigRational[] v)

    • arrayCopy

      public static void arrayCopy(Object[][] source, Object[][] destination)
      Copy a source array to a destination one. Arrays must be of same size and initialised.
      Parameters:
      source - Source array
      destination - Destination array

    • arrayCopy

      public static void arrayCopy(Object[] source, Object[] destination)
      Copy a source array to a destination one. Arrays must be of same size and initialised.
      Parameters:
      source - Source array
      destination - Destination array

    • dotprintMatrix

      public static void dotprintMatrix(BigRational[][] A)
      Parameters:
      A - A 2-dimensional matrix of BigRationals

    • max

      public static double max(double[] arr)

    • sum

      public static double sum(double[] arr)

    • sum

      public static int sum(int[] arr)

    • exp

      public static BigDecimal exp(double p, MathContext mc) throws InternalErrorException
      Parameters:
      p - Exponent of the power to be computed
      mc - MathContext object for the final precision
      Returns:
      BigDecimal representation of exp(p)
      Throws:
      InternalErrorException

    • log

      public static BigDecimal log(BigDecimal N, MathContext mc)
      Parameters:
      N - BigDecimal of which the logarithm is computed
      mc - MathContext object for the final precision
      Returns:
      BigDecimal representation of log(N)

    • logGamma

      public static double logGamma(double x)
      Uses Lanczos approximation formula to compute the LogGamma Function ref: https://introcs.cs.princeton.edu/java/91float/Gamma.java.html