org.apache.commons.math3.analysis.differentiation

## Class DSCompiler

- java.lang.Object
- - org.apache.commons.math3.analysis.differentiation.DSCompiler

    public class DSCompiler
    extends Object

Class holding "compiled" computation rules for derivative structures.

This class implements the computation rules described in Dan Kalman's paper Doubly Recursive Multivariate Automatic Differentiation, Mathematics Magazine, vol. 75, no. 3, June 2002. However, in order to avoid performances bottlenecks, the recursive rules are "compiled" once in an unfold form. This class does this recursion unrolling and stores the computation rules as simple loops with pre-computed indirection arrays.

This class maps all derivative computation into single dimension arrays that hold the value and partial derivatives. The class does not hold these arrays, which remains under the responsibility of the caller. For each combination of number of free parameters and derivation order, only one compiler is necessary, and this compiler will be used to perform computations on all arrays provided to it, which can represent hundreds or thousands of different parameters kept together with all theur partial derivatives.

The arrays on which compilers operate contain only the partial derivatives together with the 0th derivative, i.e. the value. The partial derivatives are stored in a compiler-specific order, which can be retrieved using methods `getPartialDerivativeIndex` and `getPartialDerivativeOrders(int)`. The value is guaranteed to be stored as the first element (i.e. the `getPartialDerivativeIndex` method returns 0 when called with 0 for all derivation orders and `getPartialDerivativeOrders` returns an array filled with 0 when called with 0 as the index).

Note that the ordering changes with number of parameters and derivation order. For example given 2 parameters x and y, df/dy is stored at index 2 when derivation order is set to 1 (in this case the array has three elements: f, df/dx and df/dy). If derivation order is set to 2, then df/dy will be stored at index 3 (in this case the array has six elements: f, df/dx, df/dxdx, df/dy, df/dxdy and df/dydy).

Given this structure, users can perform some simple operations like adding, subtracting or multiplying constants and negating the elements by themselves, knowing if they want to mutate their array or create a new array. These simple operations are not provided by the compiler. The compiler provides only the more complex operations between several arrays.

This class is mainly used as the engine for scalar variable `DerivativeStructure`. It can also be used directly to hold several variables in arrays for more complex data structures. User can for example store a vector of n variables depending on three x, y and z free parameters in one array as follows:

       // parameter 0 is x, parameter 1 is y, parameter 2 is z
       int parameters = 3;
       DSCompiler compiler = DSCompiler.getCompiler(parameters, order);
       int size = compiler.getSize();

       // pack all elements in a single array
       double[] array = new double[n * size];
       for (int i = 0; i < n; ++i) {

         // we know value is guaranteed to be the first element
         array[i * size] = v[i];

         // we don't know where first derivatives are stored, so we ask the compiler
         array[i * size + compiler.getPartialDerivativeIndex(1, 0, 0) = dvOnDx[i][0];
         array[i * size + compiler.getPartialDerivativeIndex(0, 1, 0) = dvOnDy[i][0];
         array[i * size + compiler.getPartialDerivativeIndex(0, 0, 1) = dvOnDz[i][0];

         // we let all higher order derivatives set to 0

       }

Then in another function, user can perform some operations on all elements stored in the single array, such as a simple product of all variables:

       // compute the product of all elements
       double[] product = new double[size];
       prod[0] = 1.0;
       for (int i = 0; i < n; ++i) {
         double[] tmp = product.clone();
         compiler.multiply(tmp, 0, array, i * size, product, 0);
       }

       // value
       double p = product[0];

       // first derivatives
       double dPdX = product[compiler.getPartialDerivativeIndex(1, 0, 0)];
       double dPdY = product[compiler.getPartialDerivativeIndex(0, 1, 0)];
       double dPdZ = product[compiler.getPartialDerivativeIndex(0, 0, 1)];

       // cross derivatives (assuming order was at least 2)
       double dPdXdX = product[compiler.getPartialDerivativeIndex(2, 0, 0)];
       double dPdXdY = product[compiler.getPartialDerivativeIndex(1, 1, 0)];
       double dPdXdZ = product[compiler.getPartialDerivativeIndex(1, 0, 1)];
       double dPdYdY = product[compiler.getPartialDerivativeIndex(0, 2, 0)];
       double dPdYdZ = product[compiler.getPartialDerivativeIndex(0, 1, 1)];
       double dPdZdZ = product[compiler.getPartialDerivativeIndex(0, 0, 2)];

Since:
  3.1
Version:
  $Id: DSCompiler.java 1421949 2012-12-14 15:53:32Z luc $
See Also:
  `DerivativeStructure`

### Field Summary

Fields
`private static AtomicReference<DSCompiler[][]>` `compilers` Array of all compilers created so far.
`private int[][][]` `compIndirection` Indirection arrays for function composition.
`private int[][]` `derivativesIndirection` Indirection array for partial derivatives.
`private int[]` `lowerIndirection` Indirection array of the lower derivative elements.
`private int[][][]` `multIndirection` Indirection arrays for multiplication.
`private int` `order` Derivation order.
`private int` `parameters` Number of free parameters.
`private int[][]` `sizes` Number of partial derivatives (including the single 0 order derivative element).

### Constructor Summary

Constructors
`private` `DSCompiler(int parameters, int order, DSCompiler valueCompiler, DSCompiler derivativeCompiler)` Private constructor, reserved for the factory method `getCompiler(int, int)`.

### Method Summary

Methods
`void` `acos(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute arc cosine of a derivative structure.
`void` `acosh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute inverse hyperbolic cosine of a derivative structure.
`void` `add(double[] lhs, int lhsOffset, double[] rhs, int rhsOffset, double[] result, int resultOffset)` Perform addition of two derivative structures.
`void` `asin(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute arc sine of a derivative structure.
`void` `asinh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute inverse hyperbolic sine of a derivative structure.
`void` `atan(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute arc tangent of a derivative structure.
`void` `atan2(double[] y, int yOffset, double[] x, int xOffset, double[] result, int resultOffset)` Compute two arguments arc tangent of a derivative structure.
`void` `atanh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute inverse hyperbolic tangent of a derivative structure.
`void` `checkCompatibility(DSCompiler compiler)` Check rules set compatibility.
`private static int[][][]` `compileCompositionIndirection(int parameters, int order, DSCompiler valueCompiler, DSCompiler derivativeCompiler, int[][] sizes, int[][] derivativesIndirection)` Compile the function composition indirection array.
`private static int[][]` `compileDerivativesIndirection(int parameters, int order, DSCompiler valueCompiler, DSCompiler derivativeCompiler)` Compile the derivatives indirection array.
`private static int[]` `compileLowerIndirection(int parameters, int order, DSCompiler valueCompiler, DSCompiler derivativeCompiler)` Compile the lower derivatives indirection array.
`private static int[][][]` `compileMultiplicationIndirection(int parameters, int order, DSCompiler valueCompiler, DSCompiler derivativeCompiler, int[] lowerIndirection)` Compile the multiplication indirection array.
`private static int[][]` `compileSizes(int parameters, int order, DSCompiler valueCompiler)` Compile the sizes array.
`void` `compose(double[] operand, int operandOffset, double[] f, double[] result, int resultOffset)` Compute composition of a derivative structure by a function.
`private static int` `convertIndex(int index, int srcP, int[][] srcDerivativesIndirection, int destP, int destO, int[][] destSizes)` Convert an index from one (parameters, order) structure to another.
`void` `cos(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute cosine of a derivative structure.
`void` `cosh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute hyperbolic cosine of a derivative structure.
`void` `divide(double[] lhs, int lhsOffset, double[] rhs, int rhsOffset, double[] result, int resultOffset)` Perform division of two derivative structures.
`void` `exp(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute exponential of a derivative structure.
`void` `expm1(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute exp(x) - 1 of a derivative structure.
`static DSCompiler` `getCompiler(int parameters, int order)` Get the compiler for number of free parameters and order.
`int` `getFreeParameters()` Get the number of free parameters.
`int` `getOrder()` Get the derivation order.
`int` `getPartialDerivativeIndex(int... orders)` Get the index of a partial derivative in the array.
`private static int` `getPartialDerivativeIndex(int parameters, int order, int[][] sizes, int... orders)` Get the index of a partial derivative in an array.
`int[]` `getPartialDerivativeOrders(int index)` Get the derivation orders for a specific index in the array.
`int` `getSize()` Get the array size required for holding partial derivatives data.
`void` `linearCombination(double a1, double[] c1, int offset1, double a2, double[] c2, int offset2, double[] result, int resultOffset)` Compute linear combination.
`void` `linearCombination(double a1, double[] c1, int offset1, double a2, double[] c2, int offset2, double a3, double[] c3, int offset3, double[] result, int resultOffset)` Compute linear combination.
`void` `linearCombination(double a1, double[] c1, int offset1, double a2, double[] c2, int offset2, double a3, double[] c3, int offset3, double a4, double[] c4, int offset4, double[] result, int resultOffset)` Compute linear combination.
`void` `log(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute natural logarithm of a derivative structure.
`void` `log10(double[] operand, int operandOffset, double[] result, int resultOffset)` Computes base 10 logarithm of a derivative structure.
`void` `log1p(double[] operand, int operandOffset, double[] result, int resultOffset)` Computes shifted logarithm of a derivative structure.
`void` `multiply(double[] lhs, int lhsOffset, double[] rhs, int rhsOffset, double[] result, int resultOffset)` Perform multiplication of two derivative structures.
`void` `pow(double[] x, int xOffset, double[] y, int yOffset, double[] result, int resultOffset)` Compute power of a derivative structure.
`void` `pow(double[] operand, int operandOffset, double p, double[] result, int resultOffset)` Compute power of a derivative structure.
`void` `pow(double[] operand, int operandOffset, int n, double[] result, int resultOffset)` Compute integer power of a derivative structure.
`void` `remainder(double[] lhs, int lhsOffset, double[] rhs, int rhsOffset, double[] result, int resultOffset)` Perform remainder of two derivative structures.
`void` `rootN(double[] operand, int operandOffset, int n, double[] result, int resultOffset)` Compute nth root of a derivative structure.
`void` `sin(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute sine of a derivative structure.
`void` `sinh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute hyperbolic sine of a derivative structure.
`void` `subtract(double[] lhs, int lhsOffset, double[] rhs, int rhsOffset, double[] result, int resultOffset)` Perform subtraction of two derivative structures.
`void` `tan(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute tangent of a derivative structure.
`void` `tanh(double[] operand, int operandOffset, double[] result, int resultOffset)` Compute hyperbolic tangent of a derivative structure.
`double` `taylor(double[] ds, int dsOffset, double... delta)` Evaluate Taylor expansion of a derivative structure.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Field Detail

#### compilers

    private static AtomicReference<DSCompiler[][]> compilers

Array of all compilers created so far.

#### parameters

    private final int parameters

Number of free parameters.

#### order

    private final int order

Derivation order.

#### sizes

    private final int[][] sizes

Number of partial derivatives (including the single 0 order derivative element).

#### derivativesIndirection

    private final int[][] derivativesIndirection

Indirection array for partial derivatives.

#### lowerIndirection

    private final int[] lowerIndirection

Indirection array of the lower derivative elements.

#### multIndirection

    private final int[][][] multIndirection

Indirection arrays for multiplication.

#### compIndirection

    private final int[][][] compIndirection

Indirection arrays for function composition.

### Constructor Detail

#### DSCompiler

    private DSCompiler(int parameters,
              int order,
              DSCompiler valueCompiler,
              DSCompiler derivativeCompiler)

Private constructor, reserved for the factory method `getCompiler(int, int)`.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
  `derivativeCompiler` - compiler for the derivative part

### Method Detail

#### getCompiler

    public static DSCompiler getCompiler(int parameters,
                         int order)

Get the compiler for number of free parameters and order.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
Returns:
  cached rules set

#### compileSizes

    private static int[][] compileSizes(int parameters,
                       int order,
                       DSCompiler valueCompiler)

Compile the sizes array.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
Returns:
  sizes array

#### compileDerivativesIndirection

    private static int[][] compileDerivativesIndirection(int parameters,
                                        int order,
                                        DSCompiler valueCompiler,
                                        DSCompiler derivativeCompiler)

Compile the derivatives indirection array.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
  `derivativeCompiler` - compiler for the derivative part
Returns:
  derivatives indirection array

#### compileLowerIndirection

    private static int[] compileLowerIndirection(int parameters,
                                int order,
                                DSCompiler valueCompiler,
                                DSCompiler derivativeCompiler)

Compile the lower derivatives indirection array.

This indirection array contains the indices of all elements except derivatives for last derivation order.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
  `derivativeCompiler` - compiler for the derivative part
Returns:
  lower derivatives indirection array

#### compileMultiplicationIndirection

    private static int[][][] compileMultiplicationIndirection(int parameters,
                                             int order,
                                             DSCompiler valueCompiler,
                                             DSCompiler derivativeCompiler,
                                             int[] lowerIndirection)

Compile the multiplication indirection array.

This indirection array contains the indices of all pairs of elements involved when computing a multiplication. This allows a straightforward loop-based multiplication (see `multiply(double[], int, double[], int, double[], int)`).

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
  `derivativeCompiler` - compiler for the derivative part
  `lowerIndirection` - lower derivatives indirection array
Returns:
  multiplication indirection array

#### compileCompositionIndirection

    private static int[][][] compileCompositionIndirection(int parameters,
                                          int order,
                                          DSCompiler valueCompiler,
                                          DSCompiler derivativeCompiler,
                                          int[][] sizes,
                                          int[][] derivativesIndirection)

Compile the function composition indirection array.

This indirection array contains the indices of all sets of elements involved when computing a composition. This allows a straightforward loop-based composition (see `compose(double[], int, double[], double[], int)`).

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `valueCompiler` - compiler for the value part
  `derivativeCompiler` - compiler for the derivative part
  `sizes` - sizes array
  `derivativesIndirection` - derivatives indirection array
Returns:
  multiplication indirection array

#### getPartialDerivativeIndex

    public int getPartialDerivativeIndex(int... orders)
                                  throws DimensionMismatchException,
                                         NumberIsTooLargeException

Get the index of a partial derivative in the array.

If all orders are set to 0, then the 0th order derivative is returned, which is the value of the function.

The indices of derivatives are between 0 and `getSize()` - 1. Their specific order is fixed for a given compiler, but otherwise not publicly specified. There are however some simple cases which have guaranteed indices:

- the index of 0th order derivative is always 0
- if there is only 1 `free parameter`, then the derivatives are sorted in increasing derivation order (i.e. f at index 0, df/dp at index 1, d2f/dp2 at index 2 ... dkf/dpk at index k),
- if the `derivation order` is 1, then the derivatives are sorted in incresing free parameter order (i.e. f at index 0, df/dx1 at index 1, df/dx2 at index 2 ... df/dxk at index k),
- all other cases are not publicly specified

This method is the inverse of method `getPartialDerivativeOrders(int)`

Parameters:
  `orders` - derivation orders with respect to each parameter
Returns:
  index of the partial derivative
Throws:
  `DimensionMismatchException` - if the numbers of parameters does not match the instance
  `NumberIsTooLargeException` - if sum of derivation orders is larger than the instance limits
See Also:
  `getPartialDerivativeOrders(int)`

#### getPartialDerivativeIndex

    private static int getPartialDerivativeIndex(int parameters,
                                int order,
                                int[][] sizes,
                                int... orders)
                                          throws NumberIsTooLargeException

Get the index of a partial derivative in an array.

Parameters:
  `parameters` - number of free parameters
  `order` - derivation order
  `sizes` - sizes array
  `orders` - derivation orders with respect to each parameter (the lenght of this array must match the number of parameters)
Returns:
  index of the partial derivative
Throws:
  `NumberIsTooLargeException` - if sum of derivation orders is larger than the instance limits

#### convertIndex

    private static int convertIndex(int index,
                   int srcP,
                   int[][] srcDerivativesIndirection,
                   int destP,
                   int destO,
                   int[][] destSizes)

Convert an index from one (parameters, order) structure to another.

Parameters:
  `index` - index of a partial derivative in source derivative structure
  `srcP` - number of free parameters in source derivative structure
  `srcDerivativesIndirection` - derivatives indirection array for the source derivative structure
  `destP` - number of free parameters in destination derivative structure
  `destO` - derivation order in destination derivative structure
  `destSizes` - sizes array for the destination derivative structure
Returns:
  index of the partial derivative with the same characteristics in destination derivative structure

#### getPartialDerivativeOrders

    public int[] getPartialDerivativeOrders(int index)

Get the derivation orders for a specific index in the array.

This method is the inverse of `getPartialDerivativeIndex(int...)`.

Parameters:
  `index` - of the partial derivative
Returns:
  orders derivation orders with respect to each parameter
See Also:
  `getPartialDerivativeIndex(int...)`

#### getFreeParameters

    public int getFreeParameters()

Get the number of free parameters.

Returns:
  number of free parameters

#### getOrder

    public int getOrder()

Get the derivation order.

Returns:
  derivation order

#### getSize

    public int getSize()

Get the array size required for holding partial derivatives data.

This number includes the single 0 order derivative element, which is guaranteed to be stored in the first element of the array.

Returns:
  array size required for holding partial derivatives data

#### linearCombination

    public void linearCombination(double a1,
                         double[] c1,
                         int offset1,
                         double a2,
                         double[] c2,
                         int offset2,
                         double[] result,
                         int resultOffset)

Compute linear combination. The derivative structure built will be a1 * ds1 + a2 * ds2

Parameters:
  `a1` - first scale factor
  `c1` - first base (unscaled) component
  `offset1` - offset of first operand in its array
  `a2` - second scale factor
  `c2` - second base (unscaled) component
  `offset2` - offset of second operand in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### linearCombination

    public void linearCombination(double a1,
                         double[] c1,
                         int offset1,
                         double a2,
                         double[] c2,
                         int offset2,
                         double a3,
                         double[] c3,
                         int offset3,
                         double[] result,
                         int resultOffset)

Compute linear combination. The derivative structure built will be a1 * ds1 + a2 * ds2 + a3 * ds3 + a4 * ds4

Parameters:
  `a1` - first scale factor
  `c1` - first base (unscaled) component
  `offset1` - offset of first operand in its array
  `a2` - second scale factor
  `c2` - second base (unscaled) component
  `offset2` - offset of second operand in its array
  `a3` - third scale factor
  `c3` - third base (unscaled) component
  `offset3` - offset of third operand in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### linearCombination

    public void linearCombination(double a1,
                         double[] c1,
                         int offset1,
                         double a2,
                         double[] c2,
                         int offset2,
                         double a3,
                         double[] c3,
                         int offset3,
                         double a4,
                         double[] c4,
                         int offset4,
                         double[] result,
                         int resultOffset)

Compute linear combination. The derivative structure built will be a1 * ds1 + a2 * ds2 + a3 * ds3 + a4 * ds4

Parameters:
  `a1` - first scale factor
  `c1` - first base (unscaled) component
  `offset1` - offset of first operand in its array
  `a2` - second scale factor
  `c2` - second base (unscaled) component
  `offset2` - offset of second operand in its array
  `a3` - third scale factor
  `c3` - third base (unscaled) component
  `offset3` - offset of third operand in its array
  `a4` - fourth scale factor
  `c4` - fourth base (unscaled) component
  `offset4` - offset of fourth operand in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### add

    public void add(double[] lhs,
           int lhsOffset,
           double[] rhs,
           int rhsOffset,
           double[] result,
           int resultOffset)

Perform addition of two derivative structures.

Parameters:
  `lhs` - array holding left hand side of addition
  `lhsOffset` - offset of the left hand side in its array
  `rhs` - array right hand side of addition
  `rhsOffset` - offset of the right hand side in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### subtract

    public void subtract(double[] lhs,
                int lhsOffset,
                double[] rhs,
                int rhsOffset,
                double[] result,
                int resultOffset)

Perform subtraction of two derivative structures.

Parameters:
  `lhs` - array holding left hand side of subtraction
  `lhsOffset` - offset of the left hand side in its array
  `rhs` - array right hand side of subtraction
  `rhsOffset` - offset of the right hand side in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### multiply

    public void multiply(double[] lhs,
                int lhsOffset,
                double[] rhs,
                int rhsOffset,
                double[] result,
                int resultOffset)

Perform multiplication of two derivative structures.

Parameters:
  `lhs` - array holding left hand side of multiplication
  `lhsOffset` - offset of the left hand side in its array
  `rhs` - array right hand side of multiplication
  `rhsOffset` - offset of the right hand side in its array
  `result` - array where result must be stored (for multiplication the result array cannot be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### divide

    public void divide(double[] lhs,
              int lhsOffset,
              double[] rhs,
              int rhsOffset,
              double[] result,
              int resultOffset)

Perform division of two derivative structures.

Parameters:
  `lhs` - array holding left hand side of division
  `lhsOffset` - offset of the left hand side in its array
  `rhs` - array right hand side of division
  `rhsOffset` - offset of the right hand side in its array
  `result` - array where result must be stored (for division the result array cannot be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### remainder

    public void remainder(double[] lhs,
                 int lhsOffset,
                 double[] rhs,
                 int rhsOffset,
                 double[] result,
                 int resultOffset)

Perform remainder of two derivative structures.

Parameters:
  `lhs` - array holding left hand side of remainder
  `lhsOffset` - offset of the left hand side in its array
  `rhs` - array right hand side of remainder
  `rhsOffset` - offset of the right hand side in its array
  `result` - array where result must be stored (it may be one of the input arrays)
  `resultOffset` - offset of the result in its array

#### pow

    public void pow(double[] operand,
           int operandOffset,
           double p,
           double[] result,
           int resultOffset)

Compute power of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `p` - power to apply
  `result` - array where result must be stored (for power the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### pow

    public void pow(double[] operand,
           int operandOffset,
           int n,
           double[] result,
           int resultOffset)

Compute integer power of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `n` - power to apply
  `result` - array where result must be stored (for power the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### pow

    public void pow(double[] x,
           int xOffset,
           double[] y,
           int yOffset,
           double[] result,
           int resultOffset)

Compute power of a derivative structure.

Parameters:
  `x` - array holding the base
  `xOffset` - offset of the base in its array
  `y` - array holding the exponent
  `yOffset` - offset of the exponent in its array
  `result` - array where result must be stored (for power the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### rootN

    public void rootN(double[] operand,
             int operandOffset,
             int n,
             double[] result,
             int resultOffset)

Compute nth root of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `n` - order of the root
  `result` - array where result must be stored (for nth root the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### exp

    public void exp(double[] operand,
           int operandOffset,
           double[] result,
           int resultOffset)

Compute exponential of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for exponential the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### expm1

    public void expm1(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Compute exp(x) - 1 of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for exponential the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### log

    public void log(double[] operand,
           int operandOffset,
           double[] result,
           int resultOffset)

Compute natural logarithm of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for logarithm the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### log1p

    public void log1p(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Computes shifted logarithm of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for shifted logarithm the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### log10

    public void log10(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Computes base 10 logarithm of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for base 10 logarithm the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### cos

    public void cos(double[] operand,
           int operandOffset,
           double[] result,
           int resultOffset)

Compute cosine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for cosine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### sin

    public void sin(double[] operand,
           int operandOffset,
           double[] result,
           int resultOffset)

Compute sine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for sine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### tan

    public void tan(double[] operand,
           int operandOffset,
           double[] result,
           int resultOffset)

Compute tangent of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for tangent the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### acos

    public void acos(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute arc cosine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for arc cosine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### asin

    public void asin(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute arc sine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for arc sine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### atan

    public void atan(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute arc tangent of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for arc tangent the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### atan2

    public void atan2(double[] y,
             int yOffset,
             double[] x,
             int xOffset,
             double[] result,
             int resultOffset)

Compute two arguments arc tangent of a derivative structure.

Parameters:
  `y` - array holding the first operand
  `yOffset` - offset of the first operand in its array
  `x` - array holding the second operand
  `xOffset` - offset of the second operand in its array
  `result` - array where result must be stored (for two arguments arc tangent the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### cosh

    public void cosh(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute hyperbolic cosine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for hyperbolic cosine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### sinh

    public void sinh(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute hyperbolic sine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for hyperbolic sine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### tanh

    public void tanh(double[] operand,
            int operandOffset,
            double[] result,
            int resultOffset)

Compute hyperbolic tangent of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for hyperbolic tangent the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### acosh

    public void acosh(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Compute inverse hyperbolic cosine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for inverse hyperbolic cosine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### asinh

    public void asinh(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Compute inverse hyperbolic sine of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for inverse hyperbolic sine the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### atanh

    public void atanh(double[] operand,
             int operandOffset,
             double[] result,
             int resultOffset)

Compute inverse hyperbolic tangent of a derivative structure.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `result` - array where result must be stored (for inverse hyperbolic tangent the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### compose

    public void compose(double[] operand,
               int operandOffset,
               double[] f,
               double[] result,
               int resultOffset)

Compute composition of a derivative structure by a function.

Parameters:
  `operand` - array holding the operand
  `operandOffset` - offset of the operand in its array
  `f` - array of value and derivatives of the function at the current point (i.e. at `operand[operandOffset]`).
  `result` - array where result must be stored (for composition the result array cannot be the input array)
  `resultOffset` - offset of the result in its array

#### taylor

    public double taylor(double[] ds,
                int dsOffset,
                double... delta)

Evaluate Taylor expansion of a derivative structure.

Parameters:
  `ds` - array holding the derivative structure
  `dsOffset` - offset of the derivative structure in its array
  `delta` - parameters offsets (Δx, Δy, ...)
Returns:
  value of the Taylor expansion at x + Δx, y + Δy, ...

#### checkCompatibility

    public void checkCompatibility(DSCompiler compiler)
                            throws DimensionMismatchException

Check rules set compatibility.

Parameters:
  `compiler` - other compiler to check against instance
Throws:
  `DimensionMismatchException` - if number of free parameters or orders are inconsistent