org.jscience.mathematics
Class ArrayMathUtils

java.lang.Object
  extended by org.jscience.mathematics.ArrayMathUtils

public final class ArrayMathUtils
extends java.lang.Object

Arrays are faster than object, so this class is here to take full advantage of arrays without encapsulation. All methods are safe, that is, they create copies of arrays whenever necessary This makes for slower methods, but the programmer can always define his own methods optimized for performance.


Method Summary
static double[] abs(double[] v)
          Takes the absolute value of each component of an array.
static double[][] abs(double[][] v)
          Takes the absolute value of each component of an array.
static int[] abs(int[] v)
          Takes the absolute value of each component of an array.
static int[][] abs(int[][] v)
          Takes the absolute value of each component of an array.
static double[] add(double[] w, double a)
          Adds a scalar to every element in the array.
static double[] add(double[] a, double[] b)
          Adds the two arrays together (componentwise).
static double[] add(double[] w, double a, double[] v, int p)
          Adds to an array w, a times v where a is a scalar.
static int[] add(int[] w, double a, int[] v, int p)
          Adds to an array w, a times v where a is a scalar.
static int[] add(int[] w, int a)
          Adds a scalar to every element in the array.
static int[] add(int[] a, int[] b)
          Adds the two arrays together (componentwise).
static java.lang.Number[] apply(NumberMapping m, java.lang.Number[] v)
          Applys a map to every component of an array.
static java.lang.Number[][] apply(NumberMapping m, java.lang.Number[][] v)
          Applys a map to every component of an array.
static double[] apply(PrimitiveMapping m, double[] v)
          Applys a map to every component of an array.
static double[][] apply(PrimitiveMapping m, double[][] v)
          Applys a map to every component of an array.
static Complex[] copy(Complex[] array)
          Returns a copy of the array.
static Complex[][] copy(Complex[][] v)
          Returns a copy of the array.
static double[] copy(double[] array)
          Returns a copy of the array.
static double[][] copy(double[][] v)
          Returns a copy of the array.
static float[] copy(float[] array)
          Returns a copy of the array.
static int[] copy(int[] array)
          Returns a copy of the array.
static int[][] copy(int[][] v)
          Returns a copy of the array.
static long[] copy(long[] array)
          Returns a copy of the array.
static double correlation(double[] v1, double[] v2)
          Computes the (linear) correlation between two arrays.
static double correlation(int[] v1, int[] v2)
          Computes the (linear) correlation between two arrays.
static double covariance(double[] v1, double[] v2)
          Computes the covariance.
static double covariance(int[] v1, int[] v2)
          Computes the covariance.
static boolean equals(double[] a, double[] b)
          Checks if two arrays are equal within a tolerance.
static boolean equals(int[] a, int[] b)
          Deprecated. Use java.util.Arrays instead.
static double[] extract(int k0, int k1, double[] invect)
          Extracts a sub-array (will invert the resulting array if k0 > k1).
static int[] extract(int k0, int k1, int[] invect)
          Extracts a sub-array (will invert the resulting array if k0 > k1).
static double getPowerN(double[] data, int n)
          Sums all components then puts to power n.
static double[] invert(double[] v)
          Inverts an array from left to right.
static int[] invert(int[] v)
          Inverts an array from left to right.
static boolean isSquare(double[][] a)
           
static boolean isSquare(float[][] a)
           
static boolean isSquare(int[][] a)
           
static boolean isSquare(long[][] a)
           
static boolean isSquare(java.lang.Object[][] a)
           
static double mass(double[] v)
          Returns the sum of the elements of the array.
static int mass(int[] v)
          Returns the sum of the elements of the array.
static double max(double[] v)
          Returns the maximum of an array.
static double max(double[][] v)
          Returns the maximum of an array.
static int max(int[] v)
          Returns the maximum of an array.
static int max(int[][] v)
          Returns the maximum of an array.
static double maxIndex(double[] value)
          returns the index of the greatest element from the given array
static double mean(double[] v)
          Computes the mean.
static double mean(int[] v)
          Computes the mean.
static double median(double[] v)
          Computes the median of an array.
static int median(int[] v)
          Computes the median of an array.
static double min(double[] v)
          Returns the minimum of an array.
static double min(double[][] v)
          Returns the minimum of an array.
static int min(int[] v)
          Returns the minimum of an array.
static int min(int[][] v)
          Returns the minimum of an array.
static double minIndex(double[] value)
          returns the index of the smallest element from the given array
static double[] mod(Complex[] v)
          Returns the componentwise modulus of an array of Complex numbers.
static double[][] mod(Complex[][] v)
          Returns the componentwise modulus of an array of Complex numbers.
static double norm(double[] data)
          Computes the L2 norm of an array (Euclidean norm or "length").
static double norm(int[] data)
          Computes the L2 norm of an array (Euclidean norm or "length").
static double[] normalize(double[] v)
          Renormalizes the array so that its L2 norm is 1 (up to computational errors).
static double[] padding(int n0, int pos, double[] v)
          Fills in with zero to get to the desired length; original array with be at the specified position.
static int[] padding(int n0, int pos, int[] v)
          Fills in with zeroes to get to the specified length; original array with be at the specified position
static double percentile(double[] v, double p)
          Gives the percentile of an array
static double percentile(int[] v, double p)
          Gives the percentile of an array.
static void print(double[] v)
          Prints an array to screen.
static void print(double[][] v)
          Prints an array to screen.
static void print(int[] v)
          Prints an array to screen.
static void print(int[][] v)
          Prints an array to screen.
static double[] range(double b)
          Generates an array going for 0 to b with steps of size 1. 0 can be smaller or larger than b.
static double range(double[] population)
          returns the difference between the max and the min element
static double[] range(double a, double b)
          Generates an array going for a to b inclusively with steps of size 1. a can be smaller or larger than b.
static double[] range(double a, double b, double step)
          Generates an array going for a to b with steps of size step.
static int[] range(int b)
          Generates an array going for 0 to b with steps of size 1. 0 can be smaller or larger than b.
static int[] range(int a, int b)
          Generates an array going for a to b with steps of size 1. a can be smaller or larger than b.
static int[] range(int a, int b, int step)
          Generates an array going for a to b with steps of size step.
static double[] scalarMultiply(double a, double[] v)
          Multiplies every component of an array by a scalar.
static double[] scalarMultiply(double a, int[] v)
          Multiplies every component of an array by a scalar.
static double[] scalarMultiplyFast(double a, double[] v)
          Fast scalar multiplication for sparse arrays.
static double[] scalarMultiplyFast(double a, int[] v)
          Fast scalar multiplication for sparse arrays.
static double scalarProduct(double[][] w0, double[][] w1)
          Computes the scalar product of two array as if they were matrices.
static double scalarProduct(double[] w0, double[] w1)
          Computes the scalar product of two array as if they were vectors.
static double scalarProduct(int[][] w0, int[][] w1)
          Computes the scalar product of two array as if they were matrices.
static int scalarProduct(int[] w0, int[] w1)
          Computes the scalar product of two array as if they were vectors.
static double[] setLengthFromBeginning(double[] data, int length)
          Sets an array to the specified length scraping or padding the end if necessary.
static int[] setLengthFromBeginning(int[] data, int length)
          Sets an array to the specified length scraping or padding the end if necessary.
static double[] setLengthFromEnd(double[] data, int length)
          Sets an array to the specified length scraping or padding the beginning if necessary.
static int[] setLengthFromEnd(int[] data, int length)
          Sets an array to the specified length scraping or padding the beginning if necessary.
static double softmax(int index, double[] x)
          produces a double between 0 and 1 based on the given array x and the index that must be between (0 and x.length) For further information see also: http://www-ccs.ucsd.edu/matlab/toolbox/nnet/softmax.html
static double[] sortMaxToMin(double[] v)
          Returns a sorted array from the maximum to the minimum value.
static int[] sortMaxToMin(int[] v)
          Returns a sorted array from the maximum to the minimum value.
static double[] sortMinToMax(double[] v)
          Returns a sorted array from the minimum to the maximum value.
static int[] sortMinToMax(int[] v)
          Returns a sorted array from the minimum to the maximum value.
static double standardDeviation(double[] v)
          Computes the (bias-corrected sample) standard deviation of an array.
static double standardDeviation(int[] v)
          Returns the (bias-corrected sample) standard deviation of an array.
static double[] subtract(double[] a, double[] b)
          Subtracts the two arrays together (componentwise)
static int[] subtract(int[] a, int[] b)
          Subtracts the two arrays together (componentwise).
static double sumSquares(double[] data)
          Sums the squares of all components; also called the energy of the array.
static double sumSquares(double[][] data)
          Sums the squares of all components; also called the energy of the array.
static int sumSquares(int[] data)
          Sums the squares of all components; also called the energy of the array.
static int sumSquares(int[][] data)
          Sums the squares of all components; also called the energy of the array.
static Complex[] toComplex(double[] v)
           
static Complex[][] toComplex(double[][] v)
           
static Complex[] toComplex(float[] v)
           
static Complex[][] toComplex(float[][] v)
           
static Complex[] toComplex(int[] v)
           
static Complex[][] toComplex(int[][] v)
           
static Complex[] toComplex(long[] v)
           
static Complex[][] toComplex(long[][] v)
           
static double[] toDouble(float[] v)
           
static double[][] toDouble(float[][] v)
           
static double[] toDouble(int[] v)
           
static double[][] toDouble(int[][] v)
           
static double[] toDouble(long[] v)
           
static double[][] toDouble(long[][] v)
           
static ExactComplex[] toExactComplex(Complex[] v)
           
static ExactComplex[][] toExactComplex(Complex[][] v)
           
static ExactComplex[] toExactComplex(double[] v)
           
static ExactComplex[][] toExactComplex(double[][] v)
           
static ExactComplex[] toExactComplex(ExactReal[] v)
           
static ExactComplex[][] toExactComplex(ExactReal[][] v)
           
static ExactReal[] toExactReal(double[] v)
           
static ExactReal[][] toExactReal(double[][] v)
           
static float[] toFloat(double[] v)
           
static float[][] toFloat(double[][] v)
           
static float[] toFloat(int[] v)
           
static float[][] toFloat(int[][] v)
           
static float[] toFloat(long[] v)
           
static float[][] toFloat(long[][] v)
           
static int[] toInt(double[] v)
           
static int[][] toInt(double[][] v)
           
static int[] toInt(float[] v)
           
static int[][] toInt(float[][] v)
           
static int[] toInt(long[] v)
           
static int[][] toInt(long[][] v)
           
static long[] toLong(double[] v)
           
static long[][] toLong(double[][] v)
           
static long[] toLong(float[] v)
           
static long[][] toLong(float[][] v)
           
static long[] toLong(int[] v)
           
static long[][] toLong(int[][] v)
           
static java.lang.String toString(double[] array)
          Returns a comma delimited string representing the value of the array.
static java.lang.String toString(double[][] array)
          Returns a comma delimited string representing the value of the array.
static java.lang.String toString(int[] array)
          Returns a comma delimited string representing the value of the array.
static java.lang.String toString(int[][] array)
          Returns a comma delimited string representing the value of the array.
static double[][] transpose(double[][] M)
          Takes the transpose of an array (like the matrix operation).
static int[][] transpose(int[][] M)
          Takes the transpose of an array (like the matrix operation).
static double variance(double[] v)
          Computes the (bias-corrected sample) variance.
static double variance(int[] v)
          Computes the (bias-corrected sample) variance.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

copy

public static int[] copy(int[] array)
Returns a copy of the array.


copy

public static long[] copy(long[] array)
Returns a copy of the array.


copy

public static float[] copy(float[] array)
Returns a copy of the array.


copy

public static double[] copy(double[] array)
Returns a copy of the array.


copy

public static Complex[] copy(Complex[] array)
Returns a copy of the array.


copy

public static Complex[][] copy(Complex[][] v)
Returns a copy of the array.


toFloat

public static float[] toFloat(double[] v)

toFloat

public static float[] toFloat(long[] v)

toFloat

public static float[] toFloat(int[] v)

isSquare

public static boolean isSquare(double[][] a)

isSquare

public static boolean isSquare(float[][] a)

isSquare

public static boolean isSquare(long[][] a)

isSquare

public static boolean isSquare(int[][] a)

isSquare

public static boolean isSquare(java.lang.Object[][] a)

toFloat

public static float[][] toFloat(double[][] v)

toFloat

public static float[][] toFloat(long[][] v)

toFloat

public static float[][] toFloat(int[][] v)

toDouble

public static double[] toDouble(float[] v)

toDouble

public static double[] toDouble(long[] v)

toDouble

public static double[] toDouble(int[] v)

toComplex

public static Complex[] toComplex(double[] v)

toComplex

public static Complex[] toComplex(float[] v)

toComplex

public static Complex[] toComplex(long[] v)

toComplex

public static Complex[] toComplex(int[] v)

toComplex

public static Complex[][] toComplex(double[][] v)

toComplex

public static Complex[][] toComplex(float[][] v)

toComplex

public static Complex[][] toComplex(long[][] v)

toComplex

public static Complex[][] toComplex(int[][] v)

toDouble

public static double[][] toDouble(float[][] v)

toDouble

public static double[][] toDouble(long[][] v)

toDouble

public static double[][] toDouble(int[][] v)

toLong

public static long[] toLong(double[] v)

toLong

public static long[] toLong(float[] v)

toLong

public static long[] toLong(int[] v)

toLong

public static long[][] toLong(float[][] v)

toLong

public static long[][] toLong(double[][] v)

toLong

public static long[][] toLong(int[][] v)

toInt

public static int[] toInt(double[] v)

toInt

public static int[] toInt(float[] v)

toInt

public static int[] toInt(long[] v)

toInt

public static int[][] toInt(float[][] v)

toInt

public static int[][] toInt(double[][] v)

toInt

public static int[][] toInt(long[][] v)

toExactReal

public static ExactReal[] toExactReal(double[] v)

toExactReal

public static ExactReal[][] toExactReal(double[][] v)

toExactComplex

public static ExactComplex[] toExactComplex(double[] v)

toExactComplex

public static ExactComplex[][] toExactComplex(double[][] v)

toExactComplex

public static ExactComplex[] toExactComplex(Complex[] v)

toExactComplex

public static ExactComplex[][] toExactComplex(Complex[][] v)

toExactComplex

public static ExactComplex[] toExactComplex(ExactReal[] v)

toExactComplex

public static ExactComplex[][] toExactComplex(ExactReal[][] v)

apply

public static double[] apply(PrimitiveMapping m,
                             double[] v)
Applys a map to every component of an array.


apply

public static double[][] apply(PrimitiveMapping m,
                               double[][] v)
Applys a map to every component of an array.


apply

public static java.lang.Number[] apply(NumberMapping m,
                                       java.lang.Number[] v)
Applys a map to every component of an array.


apply

public static java.lang.Number[][] apply(NumberMapping m,
                                         java.lang.Number[][] v)
Applys a map to every component of an array.


normalize

public static double[] normalize(double[] v)
Renormalizes the array so that its L2 norm is 1 (up to computational errors).


setLengthFromEnd

public static double[] setLengthFromEnd(double[] data,
                                        int length)
Sets an array to the specified length scraping or padding the beginning if necessary.


setLengthFromBeginning

public static double[] setLengthFromBeginning(double[] data,
                                              int length)
Sets an array to the specified length scraping or padding the end if necessary.


copy

public static double[][] copy(double[][] v)
Returns a copy of the array.


variance

public static double variance(double[] v)
Computes the (bias-corrected sample) variance.


covariance

public static double covariance(double[] v1,
                                double[] v2)
Computes the covariance.


correlation

public static double correlation(double[] v1,
                                 double[] v2)
Computes the (linear) correlation between two arrays. Squaring this result and multiply by 100 gives you the percentage of correlation.


mean

public static double mean(double[] v)
Computes the mean.


standardDeviation

public static double standardDeviation(double[] v)
Computes the (bias-corrected sample) standard deviation of an array.


sortMinToMax

public static double[] sortMinToMax(double[] v)
Returns a sorted array from the minimum to the maximum value.


sortMaxToMin

public static double[] sortMaxToMin(double[] v)
Returns a sorted array from the maximum to the minimum value.


percentile

public static double percentile(double[] v,
                                double p)
Gives the percentile of an array

Parameters:
p - percentile, must be between 0 and 1
Throws:
java.lang.IllegalArgumentException - if parameter. p is not between 0 and 1.

median

public static double median(double[] v)
Computes the median of an array. If the array contains an even number of elements, then the mean of the lower and upper medians is returned.


equals

public static boolean equals(double[] a,
                             double[] b)
Checks if two arrays are equal within a tolerance.


abs

public static double[] abs(double[] v)
Takes the absolute value of each component of an array.


abs

public static double[][] abs(double[][] v)
Takes the absolute value of each component of an array.


max

public static double max(double[] v)
Returns the maximum of an array.


max

public static double max(double[][] v)
Returns the maximum of an array.


maxIndex

public static double maxIndex(double[] value)
returns the index of the greatest element from the given array


min

public static double min(double[] v)
Returns the minimum of an array.


min

public static double min(double[][] v)
Returns the minimum of an array.


minIndex

public static double minIndex(double[] value)
returns the index of the smallest element from the given array


mod

public static double[] mod(Complex[] v)
Returns the componentwise modulus of an array of Complex numbers.


mod

public static double[][] mod(Complex[][] v)
Returns the componentwise modulus of an array of Complex numbers.


norm

public static double norm(double[] data)
Computes the L2 norm of an array (Euclidean norm or "length").


sumSquares

public static double sumSquares(double[] data)
Sums the squares of all components; also called the energy of the array.


sumSquares

public static double sumSquares(double[][] data)
Sums the squares of all components; also called the energy of the array.


getPowerN

public static double getPowerN(double[] data,
                               int n)
Sums all components then puts to power n. This is the direct computation of the polynomial expansion


scalarProduct

public static double scalarProduct(double[] w0,
                                   double[] w1)
Computes the scalar product of two array as if they were vectors.

Throws:
java.lang.IllegalArgumentException - if the don't have the same length

scalarProduct

public static double scalarProduct(double[][] w0,
                                   double[][] w1)
Computes the scalar product of two array as if they were matrices.

Throws:
java.lang.IllegalArgumentException - if the don't have the same length

extract

public static double[] extract(int k0,
                               int k1,
                               double[] invect)
Extracts a sub-array (will invert the resulting array if k0 > k1).

Parameters:
k0 - location of the first component
k1 - location of the last component

invert

public static double[] invert(double[] v)
Inverts an array from left to right.


padding

public static double[] padding(int n0,
                               int pos,
                               double[] v)
Fills in with zero to get to the desired length; original array with be at the specified position.

Parameters:
n0 - length of the new array.
pos - position of the old array.

add

public static double[] add(double[] w,
                           double a,
                           double[] v,
                           int p)
Adds to an array w, a times v where a is a scalar. Since v can be smaller then w, we must specified the position at which v will be added.

Parameters:
a - scalar.
p - position.

add

public static double[] add(double[] w,
                           double a)
Adds a scalar to every element in the array.


transpose

public static double[][] transpose(double[][] M)
Takes the transpose of an array (like the matrix operation).

Throws:
java.lang.IllegalArgumentException - if the array is not a matrix

range

public static double[] range(double a,
                             double b,
                             double step)
Generates an array going for a to b with steps of size step. If it can't get to the value b in a finite number of steps, it gets as close as possible (a can be larger or smaller than b)

Parameters:
step - size of steps, must be positive.
a - first value of array.
b - last value of array.
Throws:
java.lang.IllegalArgumentException - if step is negative of if a=b.

range

public static double[] range(double a,
                             double b)
Generates an array going for a to b inclusively with steps of size 1. a can be smaller or larger than b.


range

public static double range(double[] population)
returns the difference between the max and the min element


softmax

public static double softmax(int index,
                             double[] x)
produces a double between 0 and 1 based on the given array x and the index that must be between (0 and x.length) For further information see also: http://www-ccs.ucsd.edu/matlab/toolbox/nnet/softmax.html


range

public static double[] range(double b)
Generates an array going for 0 to b with steps of size 1. 0 can be smaller or larger than b.


add

public static double[] add(double[] a,
                           double[] b)
Adds the two arrays together (componentwise).

Throws:
java.lang.IllegalArgumentException - if the two arrays don't have the same length.

subtract

public static double[] subtract(double[] a,
                                double[] b)
Subtracts the two arrays together (componentwise)

Throws:
java.lang.IllegalArgumentException - if the two arrays don't have the same length.

scalarMultiply

public static double[] scalarMultiply(double a,
                                      double[] v)
Multiplies every component of an array by a scalar.


toString

public static java.lang.String toString(double[] array)
Returns a comma delimited string representing the value of the array.


toString

public static java.lang.String toString(double[][] array)
Returns a comma delimited string representing the value of the array.


mass

public static double mass(double[] v)
Returns the sum of the elements of the array.


scalarMultiplyFast

public static double[] scalarMultiplyFast(double a,
                                          double[] v)
Fast scalar multiplication for sparse arrays.


print

public static void print(double[] v)
Prints an array to screen.


print

public static void print(double[][] v)
Prints an array to screen.


setLengthFromEnd

public static int[] setLengthFromEnd(int[] data,
                                     int length)
Sets an array to the specified length scraping or padding the beginning if necessary.


setLengthFromBeginning

public static int[] setLengthFromBeginning(int[] data,
                                           int length)
Sets an array to the specified length scraping or padding the end if necessary.


copy

public static int[][] copy(int[][] v)
Returns a copy of the array.


variance

public static double variance(int[] v)
Computes the (bias-corrected sample) variance.


covariance

public static double covariance(int[] v1,
                                int[] v2)
Computes the covariance.


correlation

public static double correlation(int[] v1,
                                 int[] v2)
Computes the (linear) correlation between two arrays. Squaring this result and multiply by 100 gives you the percentage of correlation.


mean

public static double mean(int[] v)
Computes the mean.


standardDeviation

public static double standardDeviation(int[] v)
Returns the (bias-corrected sample) standard deviation of an array.


sortMinToMax

public static int[] sortMinToMax(int[] v)
Returns a sorted array from the minimum to the maximum value.


sortMaxToMin

public static int[] sortMaxToMin(int[] v)
Returns a sorted array from the maximum to the minimum value.


toString

public static java.lang.String toString(int[] array)
Returns a comma delimited string representing the value of the array.


toString

public static java.lang.String toString(int[][] array)
Returns a comma delimited string representing the value of the array.


percentile

public static double percentile(int[] v,
                                double p)
Gives the percentile of an array.

Parameters:
p - percentile, must be between 0 and 1
Throws:
java.lang.IllegalArgumentException - if parameter p is not between 0 and 1.

median

public static int median(int[] v)
Computes the median of an array. If the array contains an even number of elements, the lower median is returned.


equals

public static boolean equals(int[] a,
                             int[] b)
Deprecated. Use java.util.Arrays instead.

Use java.util.Arrays instead. Check if two arrays are equal.


abs

public static int[] abs(int[] v)
Takes the absolute value of each component of an array.


abs

public static int[][] abs(int[][] v)
Takes the absolute value of each component of an array.


max

public static int max(int[] v)
Returns the maximum of an array.


max

public static int max(int[][] v)
Returns the maximum of an array.


min

public static int min(int[] v)
Returns the minimum of an array.


min

public static int min(int[][] v)
Returns the minimum of an array.


norm

public static double norm(int[] data)
Computes the L2 norm of an array (Euclidean norm or "length").


sumSquares

public static int sumSquares(int[] data)
Sums the squares of all components; also called the energy of the array.


sumSquares

public static int sumSquares(int[][] data)
Sums the squares of all components; also called the energy of the array.


scalarProduct

public static int scalarProduct(int[] w0,
                                int[] w1)
Computes the scalar product of two array as if they were vectors.

Throws:
java.lang.IllegalArgumentException - if the don't have the same length.

scalarProduct

public static double scalarProduct(int[][] w0,
                                   int[][] w1)
Computes the scalar product of two array as if they were matrices.

Throws:
java.lang.IllegalArgumentException - if the don't have the same length.

extract

public static int[] extract(int k0,
                            int k1,
                            int[] invect)
Extracts a sub-array (will invert the resulting array if k0 > k1).

Parameters:
k0 - location of the first component.
k1 - location of the last component.

invert

public static int[] invert(int[] v)
Inverts an array from left to right.


padding

public static int[] padding(int n0,
                            int pos,
                            int[] v)
Fills in with zeroes to get to the specified length; original array with be at the specified position

Parameters:
n0 - length of the new array.
pos - position of the old array.

add

public static int[] add(int[] w,
                        double a,
                        int[] v,
                        int p)
Adds to an array w, a times v where a is a scalar. Since v can be smaller then w, we must specified the position at which v will be added.

Parameters:
a - scalar.
p - position.
w - longer array.
v - shorter array.
Throws:
java.lang.IllegalArgumentException - if the second array is not shorter than the first one.

add

public static int[] add(int[] w,
                        int a)
Adds a scalar to every element in the array.


range

public static int[] range(int a,
                          int b)
Generates an array going for a to b with steps of size 1. a can be smaller or larger than b.


range

public static int[] range(int b)
Generates an array going for 0 to b with steps of size 1. 0 can be smaller or larger than b.


range

public static int[] range(int a,
                          int b,
                          int step)
Generates an array going for a to b with steps of size step. If it can't get to the value b in a finite number of steps, it gets as close as possible (a can be larger or smaller than b)

Parameters:
step - size of steps, must be positive
a - first value of array
b - last value of array
Throws:
java.lang.IllegalArgumentException - if step is negative or if a=b.

transpose

public static int[][] transpose(int[][] M)
Takes the transpose of an array (like the matrix operation).

Throws:
java.lang.IllegalArgumentException - if the array is not a matrix

add

public static int[] add(int[] a,
                        int[] b)
Adds the two arrays together (componentwise).

Throws:
java.lang.IllegalArgumentException - if the two arrays don't have the same length.

subtract

public static int[] subtract(int[] a,
                             int[] b)
Subtracts the two arrays together (componentwise).

Throws:
java.lang.IllegalArgumentException - if the two arrays don't have the same length.

mass

public static int mass(int[] v)
Returns the sum of the elements of the array.


scalarMultiply

public static double[] scalarMultiply(double a,
                                      int[] v)
Multiplies every component of an array by a scalar.


scalarMultiplyFast

public static double[] scalarMultiplyFast(double a,
                                          int[] v)
Fast scalar multiplication for sparse arrays.


print

public static void print(int[] v)
Prints an array to screen.


print

public static void print(int[][] v)
Prints an array to screen.